Possession of information about the physiological characteristics of rodents is usually the prerogative of zoologists and veterinarians. However, it is also useful for owners to know what the anatomy of a rat is. This will allow you to understand the relationship between care, nutrition and possible diseases. Also, a clear understanding of how the pet is built ensures a quick response to signals of pain and discomfort.
During the external primary examination, a significant amount of hair can be noted on the entire body. This is a sign of this class of mammals. The main functions of wool:
The body of an animal is made up of:
The animal's head is large relative to the body. The muzzle is pointed, the back section is adjacent to a short neck. The skull of a rat includes 3 sections:
The muzzle is divided into:
At the end of the muzzle are vibrissae - bristles designed for touch. Rats are characterized by the presence of a nictitating membrane and a red glow of the eyes.
Experts divide the body of a rodent into 3 sections:
The limbs of the animals have five fingers. On the feet they are larger than on the hands. The soles and palms are characterized by the absence of hairline.
The tail of rodents is thick, accounting for 85% of the total body length. The female has a longer tail. The surface is covered with scaly rings and yellow fat. Instead of wool, there are bristles.
Female animals are characterized by 6 pairs of nipples, two of which are in the armpits, one on the chest and three on the belly. Outside the gestation period, they are hidden by thick hair. by examining the back: in females, the rump is in the shape of a triangle, and in males it differs in the shape of a cylinder.
Sexually mature males can reach a weight of 400 g. Females are much smaller.
The skeletal system of the animal consists of bone and cartilage parts, and includes 264 bones various shapes and magnitude. The cranium has an elongated shape. There are several sections of the spine:
The vertebral part in the rat skeleton is characterized by more than 2 dozen discs.
Despite the fact that the skeleton of a rodent looks completely different than the human skeletal system, many scientists argue that when stretching the spine, a reduced copy of the human individual will be obtained, up to the similarity in the location of individual bones.
The anatomical atlas also informs about what the general arrangement of the internal organs of the rodent looks like.
This information can be obtained visually if an autopsy of the rat is performed. After the start of the procedure, the diaphragm opens first, which separates the thoracic and abdominal regions.
Directly below the diaphragm is the rat liver. It is bright red in color and partially covers the pear-shaped stomach.
Below, the volumetric mass of the intestinal tract opens. It is covered with an omentum - an organ for the accumulation of animal fat.
A characteristic feature of this species of rodents is the absence of a gallbladder. Bile is supplied through the duct from the liver directly to the duodenum.
But rodents have an elongated spleen, located to the left of the stomach.
If the intestines are removed from abdominal cavity, then a pair of bean-shaped buds is found at the bottom. They are located asymmetrically - the left one is deepened under the pressure of the stomach. The ureters lead to the bladder located in the lower abdomen. The testes of males and the complex reproductive organs of female rats are also present there.
The vascular system is clearly represented by the inferior vena cava for the outflow of blood into the heart from the organs of the peritoneum. It also finds the aorta, which is necessary for a full blood supply to the hind limbs.
When examining the chest cavity, a pair of pink lungs and a heart with large vessels are immediately visible. The lungs hang freely on the bronchi, and are not attached to the chest. Deeper is the esophagus, which connects the pharynx with the stomach.
When studying the internal structure of a rat, it is important to remember such an organ as the brain. Like many mammals, it has several departments responsible for mental functions. Experts divide the rat brain into 4 parts, each of which has a complex structure.
Veterinarians and biologists, studying the anatomical and, noted a number of curious facts:
Important! The pain threshold of rodents is very high, the animal gives a signal about the presence of pain only with extremely severe symptoms. This leads to frequent late diagnosis of serious pathologies, so the owners of the animals should not neglect preventive examinations of their pets.
Anatomy of a rat: internal structure of organs and features of the skeleton
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The lifespan of a rat is about 3 years; at the age of 6 - 8 months, males reach a mass of 250 g, and females - somewhat less. A mature animal has a mass of 200 - 400 g.
An external examination of the body of a rat shows the presence of a significant hairline - one of the characteristic features of the class of mammals. The hairline is developed on almost all parts of the body, with the exception of the tip of the nose, the inner surface of the auricles, the palmar surfaces and the sole from the fingers to the tarsal joints. The cover performs a thermally insulating function, participates in touch, protects the skin from damage, and provides species-specific coloration.
The body - corpus - consists of a head, neck, torso, limbs and tail.
Head- caput - relatively large, elongated, its front section, called the muzzle, is pointed; rear separation from the body short neck- cervix. Head areas- regiones capitis - include areas of the dorsocaudal part of the head - areas of the skull- regiones cranii - and areas of the rostroventral, or facial part of the head - muzzle area- regiones faciei. The regions of the skull are represented frontal area- regiones frontalis, parietal- regiones parietalis, occipital- regiones occipitalis - and temporal areas- regiones temporalis, located above the corresponding bones of the skull. The areas of the muzzle include eye socket- regiones orbitalis, nose- regiones nasalis, mouth- regiones oralis, buccal region- regiones buccalis, chewing area- regiones masseterica. Along the lateral and anterior edges of the muzzle is located oral fissure- rima oris, leading to the oral cavity.
External nose- nasus externus - located above the upper lip, at its top are close to each other nostrils- nares. In the region of the end of the muzzle, lateral to the tip of the nose, single hairs protrude sharply above the general fur cover - bristles, called tactile hair (vibrissae)- pili tactiles (vibrissae) - and serving as organs of touch. Large eyes- oculi - located frontally in deep eye sockets- orbitae - and are protected by mobile upper and lower eyelids- palpebrae superior et inferior. The third eyelid is visible in the medial corner of the eye, or nictitating membrane, - membrana nictitans, which, moving along the surface of the eye, moisturizes and cleanses it. On the dorsolateral surface of the head, caudal to the eyes, is located outer ear- auris externus, which is represented by a long standing auricle- auricula - and external auditory canal- meatus acusticus externus, going from the base of the auricle deep into the temporal bone. 
torso- truncus - slightly expands in the direction from the head, subdivided into the dorsal-thoracic, lumbar-abdominal and sacro-buttock sections. In the dorsal part thoracic region distinguish cranial - interscapular- regiones interscapularis - and caudal - dorsal- regiones dorsalis - areas. The paired lateral part of this department is called costal region- regiones costalis, and the ventral part - sternal region- regiones sternalis. Lumbar-abdominal subdivided into lumbar region- regiones lumbalis - and belly area- regiones abdominis, which in turn includes area of the xiphoid process- regiones xiphoidea, umbilical region- regiones umbilicalis, groin- regiones inguinalis - and iliac region- regiones iliaca. sacro-gluteal region consists of sacral region- regiones sacralis, gluteal region- regiones glutea (glutaea), anal area- regiones analis - and perineal area- regiones perinealis.
thoracic limb includes axillary region- regiones axillaris, shoulder area- regiones brachii, elbow area- regiones cubiti, forearm area- regiones antebrachii - and brush area- regiones carpi. pelvic limb includes thigh area- regiones femoris, lower leg area- regiones cruris, heel area- regiones calcanei, tarsal region- regiones tarsi, metatarsal area- regiones metatarsi.
The eyelids are well developed, and with the exception of the nictitating membrane (supported by the semilunar cartilage) in the medial corner of the eye, only the cornea is visible, the eyelashes are very thin and short, and the cartilage glands of the eyelids (meibomian glands) are large and easily visible. Unlike cats and other predators, which have a bright green "glow" of the eyes (due to the reflective membrane), the "glow" of the eyes of the rat is red.
The nostrils of the rat are shaped like inverted commas, open laterally, and can close underwater. In rats, a vertical furrow begins just below the nostrils and forms a cleft in the upper lip, exposing the upper incisors even when the mouth is closed. Behind the incisors, the lips, covered with hair, continue inward towards the midline and the opposite halves are practically united; thus the upper incisors are isolated from the oral cavity proper.
The thoracic and pelvic limbs of rats are five-fingered. On the brush thoracic limb the first (thumb) toe is significantly reduced and looks like a short, blunt stump. Despite this, it must be considered as a separate finger, having two distinct phalanges and a fully formed, specific flat claw, in contrast to the claws of other fingers. The remaining four well-developed fingers are designated from II to V, starting from the front edge. Each finger ends with a claw - unguicula, shaped like a rounded pyramid, hollow from the ventral surface. Characteristic tubercles (rollers) are clearly visible on the brush: five digital tubercles- tori digitales - on the tips (tops) of the fingers, three interdigital tubercles on the palm (the first interdigital tubercle disappeared due to a decrease in the first finger) and two at the base of the palm - tenar tubercle (elevation of the thumb) - thenar on the radial side of the palm and hypothenar tubercle - (elevations of the little finger) - hypothenar - on the ulnar side. On the foot pelvic limb all five toes are well developed, the hairless area of the skin of the sole extends to the tarsal joint. The toes are larger than the fingers. Five digital tubercles, four interdigital and two additional metatarsal tubercles are distinguished on the foot: one is medial, the other is lateral. There is no hair on the palms and soles of rats, but the dorsal surfaces of the paws are rarely covered with short, thin hair.
Tail- cauda, actively used as a balancing organ, is thick in the white rat, shorter than the total length of the body and head and makes up about 85% of the body length (unlike the black rat). Female white rats have a relatively longer tail than males. The entire surface of the tail is covered with rings of scales that overlap one another like shingles or shingles. There is no hair on the tail, but three rather short setae emerge from under the edge of each scale. The surface of the tail is covered with orange-yellow waxy fat.
In female rats, the number of nipples usually reaches 12. Three pairs of nipples are located in the chest area: one pair of chest and two - axillary, and three pairs in the abdomen: one pair of abdominal nipples and two - inguinal. Sometimes one nipple from the second pair of axillary nipples is missing. In non-pregnant and non-lactating females, the nipples are often hidden in the coat. 
The sex of a mature rat can be determined by examining the body from the dorsal or ventral side and simply determining the shape of the caudal line of the body: the rump in the female tapers towards the tail in the form of a characteristic triangle, while in males it takes on a rounded or cylindrical shape. The external genitalia of the female include the clitoris and vagina. The clitoris, a small homologue of the male penis, is surrounded by a skin sac, the prepuce. The urethral opening opens at the base of the clitoris. Between the clitoris and the anus - anus, closer to the first, is the vagina, the opening of which is closed in the first 10 weeks of life (before puberty) by the hymen. Male external genitalia unlike the female, they are represented by a common urogenital opening of the preputial sac. In the normal state, the penis of the male is hidden in the prepuce. Caudal to the opening of the preputium are paired skin sacs of the scrotum, in which the testes are located. The sacs appear to be fused ventrally and partly divided dorsally. The large testicles give the appearance of a rather bulbous scrotum, resulting in a characteristic caudal trunk line. The anus is hidden by the nearby scrotum and the hair covering it.
1. A.D. Nozdrachev, E.L. Polyakov, "Anatomy of a rat", Publishing house "Lan", 2001.
2. T. McCracken and R. Keiner, Veterinary practice "Atlas of anatomy of small domestic animals", Aquarium Publishing House.
0L4 urogenital apparatus (genitourinary system) - apparatus urogenitalis (systema urogenitale) - is a set of anatomically and functionally interconnected organs of the excretory and reproductive systems; includes urinary organs, internal and external genital organs of the male, internal and external genital organs of the female, perineum. This section also discusses the peritoneum.
The urinary organs - organa urinaria - include the kidney, ureter and bladder.
Kidney - hep (Fig. 1) - a paired formation, bean-shaped, Brown, with a smooth surface. The kidneys are located retroperitoneally in the lumbar region between the III-V lumbar vertebrae on both sides of the dorsal aorta. The right kidney is usually located 1-2 cm cranial to the left. On the surface of the kidney is a fibrous capsule - capsula fibrosa. Each kidney is surrounded on the outside by a significant amount of perirenal adipose tissue, which makes up the fatty capsule - capsula adiposa. The kidney and fatty capsule are enclosed in two sheets of the renal fascia - f. renalis. In the kidney, a convex lateral edge is distinguished - margo lat. - and a concave medial edge - margo med., ventral and dorsal surfaces - faciei ventr. et dors., cranial end - extremitas cran. - and caudal end - extremitas caud. In the medial edge of the kidney are the renal gates - hilus renalis, through which the vessels and nerves enter the kidney and the ureter exits. The gate expands and forms a cavity in the kidney, called the renal sinus - sinus renalis; it contains fat and connective tissue surrounding the renal pelvis and vessels. The expanded proximal end of the ureter inside the sinus is the renal pelvis - pelvis renalis.
In a rat, as in other laboratory animals (cat, dog), the kidneys are single-papillary, that is, a single renal papilla, papilla renalis, freely protrudes into the pelvis, on which papillary openings are visible - forr. papillaria - small urinary tubules. The renal pelvis is the beginning of the ureter.
On the section of the kidney, the outer peripheral light urinary zone is visible - the cortex of the kidney - cortex renis, and the darker urinary part located in the center - the medulla of the kidney - medulla renis, containing the renal pyramid - rumis renalis. The base of the pyramid - basis pyramidis - is located in the cortical substance of the kidney, and the top is the renal papilla, protruding into the pelvis.
Innervation - renal branches of truncus vagalis dors., renal branch n. splanchnicus minor, renal plexus (or node) from pi. aorticus abdominalis; blood supply a. renalis.
Ureter - ureter (Fig. 2) - a paired organ, the excretory duct of the kidneys, which drains urine outward into the bladder. It emerges from the renal pelvis at the renal hilum dorsal to the entry point of the renal arteries and veins, and extends caudally, surrounded by a layer of adipose tissue, dorsally under the loin. Before entering the pelvic cavity, the ureter is located dorsal to the colon. In male rats, the ureters run dorsal to the internal pudendal arteries and veins, run caudomedial, ventral to the iliolumbar and common iliac arteries and veins, and cross the vas deferens dorsally. In females, the ureter passes dorsal to the ovarian arteries and veins, runs caudomedially, passes ventral to the iliopsoas and common iliac arteries and veins, and wraps around the uterine horn dorsally.
The ureter flows into the bladder in its caudolateral part at a short distance from the neck of the bladder. When the bladder fills, the ureters are compressed, which prevents the reverse flow of urine. The right and left ureters open into the cavity of the bladder separately, opposite each other at a short distance. The openings of the ureters are surrounded by an elevation of the mucous membrane of the bladder. In the ureter, the abdominal part - pars abdominalis - and the pelvic part - pars pelvina are distinguished. The wall of the ureter consists of three layers: the outer connective tissue, the muscular membrane - tun. muscularis, including the outer longitudinal and circular layers of smooth muscle fibers, and the mucous membrane.
Innervation - nerves and nerve plexuses (pi. uretericus) of the abdominal and pelvic parts of the autonomic nervous system; blood supply - ureteral branch a. renalis, ureteral branch a. vesicalis caud.
Rice. 1 Longitudinal section of the kidney (diagram)
1 - extremitas caud., 2 - hilus renalis, 3 - sinus renalis, 4 - margo med., 5 - extremitas cran., 6 - lobi renales, 7 - margo lat., 8 - basis pyramidis, 9 - medulla renis, 10 - cortex renis. 11 - columnae renales, 12 - pyrainis renalis.
Rice. 2 Male genitourinary system (ventral side)
1 - ren, 2 - coagulating gland, 3 - gl. d. rieferentis, 4 - vesica urinaria, 5 - d. deferens, 6 - urethra masculina, 7 corp. epididyinidis, 8 - testis, 9 - penis, 10 - cauda epididyinidis, 11 - cap- epididyinidis, 12 - gll. preputiales, 13 - gl. bul bourethralis, 14 - prostata, 15 - gl. vesicularis, 16 - ureter.
The bladder - vesica urinaria (Fig. 2) - is a hollow pear-shaped organ with an expanded blind cranial end - the top of the bladder - apex vesicae (vertex vesicae), a caudally elongated body of the bladder - corp. vesicae, passing into the narrow neck of the bladder - cervix vesicae. Dorsal surface - facies dors. - the bubble is attached to the rectum in males, in females - to the vagina; ventral surface - facies ventr. - facing the abdominal wall. In males, the bladder is surrounded ventrally and laterally by the prostate glands and seminal vesicles; in females, there is a large amount of adipose tissue around the bladder.
Outside, the bladder is covered with peritoneum. It is attached with its ventral surface to the pelvic symphysis and to the white line with the help of the median cystic ligament - lig. vesica medianum.
Lateral cystic ligament - lig. vesicae lat. - is a fold of the peritoneum that attaches the bladder to the dorsolateral wall of the pelvis in males and to the broad ligament of the uterus in females. It consists of a round ligament of the bubble - lig. teres vesicae - the germinal remnant of the umbilical artery.
Outside, the wall of the bladder is covered with a visceral peritoneum - a serous membrane - tun. serosa. The thin connective tissue layer between the serous and muscular membranes is called the subserous base - tela subserosa. The muscular membrane of the bladder includes two longitudinal layers and a circular layer of smooth muscle fibers located between them. The term "sphincter of the bladder - m. sphincter vesicae" is currently excluded due to lack of evidence for the existence of such a sphincter separate from the striated muscle of the urethra (urethra). Behind the muscular layer is a thin layer of connective tissue with vessels - the submucosa - tela submucosa, followed by a mucous membrane covered with transitional epithelium. In the collapsed bladder, the mucous membrane is thick, folded. From each ureteral orifice - ost. ureteris - in the wall of the bladder to the internal opening of the urethra - ost. urethrae int. - there is a ureteral fold - plica ureterica. The folds are the lateral borders of the vesical triangle - trigonum vesicae - a smooth section of the mucous membrane between the ureteral openings and the internal opening of the urethra.
The urethra begins caudally from the bladder, which in females is represented by a short tube opening at the head of the clitoris. In males, the structure of the urethra is more complex.
Innervation - pi. vesicales cran. et caud., nn. pelvini; blood supply - aa. vesicales cran. et caud.
The genital organs of the male - organa genitalia masculina - consists of the testes, appendages of the testes, vas deferens and accessory gonads.
Testis - testis (Fig. 3, see Fig. 2) - a paired male gonad ovoid. In the embryonic state, the testes are laid next to the kidneys; on the 30-40th day of development, they descend (as usually occurs in rodents) ventrally through the remaining open inguinal canal into the sac-like scrotum, where they are suspended on the spermatic cord. Outside of sexual activity, the testicles may be drawn back into the abdominal cavity. The testis has a head end - extremitas capitata, which is connected with the head of the epididymis, located cranially, and a tail end - extremitas caudata, connected with the tail of the epididymis located caudally. There are lateral and medial surfaces - facies lat. et med.; the first remains free, the body of the epididymis is attached to the second. The ventral edge of the testis is called free - margo liber, and the dorsal edge, adjacent to the epididymis of the testis, is called the adnexal edge - margo epididymalis.
The skeleton of the testis is formed by a dense white connective tissue protein membrane - tun. albuginea, which deeply protrudes into the tissue of the testis in the form of an axial cord - the mediastinum of the testis (maxillary body) - mediastinum testis (corp. Highmori). From the latter to the periphery of the organ, numerous interlobular partitions of the testis - lobuli testis stretch, separating the lobules of the testis - septula testis from each other. The main functioning tissue - the glandular tissue elements of the organ - the parenchyma of the testis - parenchyma testis - is represented by the seminiferous tubules. They include the convoluted seminiferous tubules - tubuli seminiferi contorti, located in the lobules, and the direct seminiferous tubules - tubuli seminiferi recti, going from the convoluted tubules to the testis network - rete testis; the network is a set of tubules in the mediastinum, connecting the direct seminiferous tubules with the efferent tubules of the testis.
Epididymis - epididymis (Fig. 3, see Fig. 2) - A long sinuously curved thin tube into which spermatozoa that have formed in the convoluted seminiferous tubules enter. In the appendage, the head, body and tail are distinguished. The head of the appendage of the testis - cap. epididymidis - has the shape of a bulb, is located at the head end of the testis, is functionally connected with it and contains lobules (cones) of the epididymis of the testis - lobuli epididymidis (coni epididymidis). They house the curved efferent tubules of the testis - ductuli efferentes testis, running from the network of the testis to the duct of the epididymis. The body of the epididymis - corp. epididymidis - the narrowest part, connects the head with the tail and contains a strongly convoluted (exceeds the body length by more than 25 times) duct of the epididymis - d. epididymidis, which, expanding, forms the tail of the epididymis - cauda epididymidis, the latter continues into the vas deferens.
Rice. 3 Testis and epididymis
1-a. testicularis, 2 - g. epididymalis, 3 - pi. painpiniformis, 4 - vessels to adipose tissue, 5 - cap. epididymidis, 6 - a. et v. testiculares, 7 - testis, 8 - corp. epididymidis, 9 - cauda epididymidis, 10 - vasa d. deferentis, 11-d. deferens.
The vas deferens - d. deferens (see Fig. 2, 3) - is a continuation of the tail of the appendage, its initial part is still tortuous, then flat. Together with the vessels and nerves of the testis, the duct rises cranially as part of the membranes of the testis, passes through the vaginal opening into the abdominal cavity. Both vas deferens run medially, pass ventral to the ureters, and empty into the urethra, the common outlet of the male's urinary and genital tracts. Not far from the confluence of the vas deferens, a well-camouflaged bladder and the prostate gland is a small steam gland of the vas deferens - gl. d. defferentis (sometimes called the ampulla gland), often omitted from description.
The wall of the vas deferens consists of an external connective tissue adventitial serous, smooth muscle and mucous membranes.
To accessory sex glands - gll. genitales accessoriae (see Fig. 2) - include paired vesicular, coagulating, prostate and bulbourethral glands. The products produced by these glands are part of the liquid part of the sperm - the seminal fluid.
Bubble gland (seminal vesicles) - gl. vesicularis (vesiculae seminales) - in rats it is large, tubular, lobed, with the exception of a rather smooth tip, bent inside the gland. It is located at the neck of the bladder, from here it goes craniolaterally; opens into the anterior part of the urinary tract. The gland is located in a capsule, a single one for the coagulating gland; the gland tissue is covered with an outer connective tissue adventitia, followed by muscular and mucous membranes.
The coagulating gland is narrow with a widened cranial end, closely adjacent to the vesicular gland along its internal bend. Previously considered as an additional, or third, prostate gland. After the gland is husked from the common capsule with the vesicular gland, it looks rather villous.
The prostate gland - prostata - is relatively small, bilobed, covers the proximal end of the vas deferens; located along the lateral wall of the urethra, into which it opens with multiple excretory prostatic ducts - ductuli prostatatici. The gland is supported by fascia from the bladder. The basis of the organ is the glandular parenchyma - parenchima glandulare, enclosed in the capsule of the prostate gland - capsula prostatae, containing smooth muscle fibers. In addition, a partition diverges through the tissue of the gland from the center to the capsule - the muscular substance - substantia muscularis, consisting of a large number of smooth muscle fibers.
Bulbourethral gland - gl. bulbourethralis - small, pear-shaped, with a smooth surface, has a lobed structure; often called the bulbous gland of the urethra, or Cooper's gland, - gl. Cowperi. Adjacent to the bulbous-cavernous muscle and covered by the ischiocavernosus muscle; opens with a duct into the caudal part of the urethra near the point of attachment of the bulbocavernosus muscle to the penis. It has a capsule consisting of striated muscle fibers.
External genital parts (organs) of the male - partes (organa) genitales masculinae ext. - include the penis, male urethra and scrotum.
The penis - penis (Fig. 4, see Fig. 2) - is a relatively small cylindrical, dense copulatory organ of the male. In the penis, the root, legs, body, back, head and prepuce are distinguished. Root of the penis - rad. penis, is directed caudally and consists of two legs and a bulb. The leg of the penis - crus penis - is the proximal end of each cavernous body, is attached to the ischial tuberosity and is covered by the ischiocavernosus muscle. The body of the penis - corp. penis - the main trunk of the organ from the root to the head; along the length of the body passes the furrow of the urethra - sul. urethralis, which houses the spongy body and urethra. The back of the penis - dorsum penis - the dorsal side of the organ during erection, the surface opposite the urethral surface - facies urethralis. The part of the penis located distal to the place of attachment of the prepuce is called the free part of the penis - pars libera penis.
Rice. 4 Penis of a gray rat: structural diagram (A), glans penis from above (B), penis bone from below (C) and from the side (D)
1 - trident, 2 - papilla ventr., 3 - papilla lat.. 4 - Corp. penis, 5 - os penis (prong).
The head of the penis - glans penis - is the distal expanded end of the organ, contains the spongy body of the head and is the external extended continuation of the albuginea of the cavernous bodies. The free part of the penis outside the erection (tension) is covered with a spacious shell - preputium (foreskin) - preputium (praeputium). During copulation, erection of the penis causes it to be pushed out of the prepuce. This sac-like formation consists of two skin folds - outer and inner plates - laminae ext. et int. The latter is attached to the penis at the proximal end of its free part. Between the inner plate and the free part of the penis, a preputial cavity is formed - cavum preputiale, into which paired preputial glands - gll open. preputiales. The glands are relatively large, pear-shaped, located immediately under the skin along the prepuce and empty the contents into the preputial cavity near the preputial opening - ost. preputiale.
According to Argiropulo (1940), for the gray rat, the characteristic features of the structure of the penis are: the head is cylindrical, its sides are slightly convex or parallel; on the side of the head, below the midline, a deep groove runs along both sides of the distal part. The annular fold slightly protrudes from the opening of the head. The central papilla - papilla centralis - is completely ossified, strongly compressed from the sides and almost does not protrude from the head; lateral papillae - papillae lat. - relatively large, dorsal papilla - papilla dors. - unpaired, central. Like other rodents, in the rat, at the distal end of the penis, on its ventral wall, there is a single cartilaginous or bone process - the bone of the penis - os penis; shortened and massive, it has a relatively poorly developed main part.
The penis consists of paired cavernous bodies and a spongy body. Cavernous body of the penis - corp. cavernosum penis - surrounded by a dense white fibrous protein membrane of the cavernous bodies - tun. albuginea corporum cavernosorum, from which fibromuscular septa extend inward - trabeculae of the cavernous bodies - trabeculae corporum cavernosorum. The latter separate from each other the cells of the cavernous bodies - cavernae corporum cavernosorum, which are vascular cavities filled with blood. Cavernous bodies in the form of two columns of spongy tissue, capable of straining when filled with blood, lie along the back of the penis; the bodies are separated by the median septum of the penis - septum penis. The volume, density and elasticity of the cavernous bodies vary depending on the degree of their blood filling. In the cavernous bodies are the terminal branches of the deep artery of the penis, the so-called helical arteries - aa. helicinae, coiled and closed in the collapsed state of the penis and opening into caverns during erection. Cavernous veins - w. cavernosae - drain blood from the spaces of the cells of the cavernous tissue.
Spongy body of the penis - corp. spongiosum penis (formerly called the cavernous body of the urethra) - is an unpaired cylindrical formation with thickenings at the ends, similar in structure to the cavernous bodies. Located around the urethra. The caudal expansion of the spongy body is called the bulb of the penis - bulbus penis. As in the cavernous bodies, in the spongy body there are trabeculae of the spongy body - trabeculae corporis spongiosi - and cells of the spongy body - cavernae corporis spongiosi.
The penis has a superficial and deep fascia and a ligament that supports it. Superficial fascia of the penis - f. penis superficialis - extends to the glans penis and into the prepuce and continues into the superficial perineal fascia, scrotal septum, and internal seminal fascia. Deep fascia of the penis - f. penis profunda - closely surrounds the cavernous bodies and the spongy body of the penis, mixes with the suspensory ligament of the penis and passes into the perineal membrane. The ligament that supports the penis is lig. suspensorium penis - is a bilateral plate, consisting of collagen fibers of the connective tissue; runs from the caudal part of the pelvic symphysis to the cavernous bodies and includes the dorsal vessels and nerves of the penis.
Innervation - n. dors, penis; blood supply a. dors, penis, a. profunda penis, a. bulbi penis.
The male urethra (male urethra) - urethra masculina (see Fig. 2) - starts from the neck of the bladder at the confluence of the vas deferens and ends at the head of the penis with the external opening of the urethra (urethra) - ost. urethrae ext., a common opening for the urinary and genital tracts. In the urethra, the pelvic part - pars pelvina - and part of the penis - pars penina are distinguished; in the first, additional sex glands open, the second is surrounded by the spongy body of the penis. The area of the urethra associated with the lobes of the prostate gland is called the prostate - pars prostatica. The muscular membrane of the pelvic part is represented by smooth muscle fibers that surround the spongy layer - str. spongiosum - cavernous tissue. Outside of the muscular membrane are striated fibers of the muscle of the urethra.
Innervation - nn. corporiscavernosi penis; blood supply - urethral branches a. rectalis media, urethral branch a. penis.
The scrotum - scrotum - is a skin pouch covered with wool, in which the testes are located.
The scrotum can only conditionally be called the external genital organ, since outside the period of enhanced spermatogenesis (when the testicles increase), there is no typical skin sac and it barely protrudes. Internally, the scrotum is a paired caudal protrusion of the abdominal cavity, in which the testis and its appendage are located. From them in the cranial direction comes the spermatic cord - funiculus spermaticus - an anatomical formation located in the scrotum and inguinal canal, which is the vas deferens running parallel to each other, its arteries and veins, the testicular artery and vein, the efferent lymphatic vessels, the pampiniform venous plexus and the testis nerve plexuses surrounded by common sheaths, represented by the muscle that lifts the testis, and several fascia.
The inner serous membrane of the scrotum - the vaginal membrane - tun. vaginalis - is a protrusion of the peritoneum; consists of two plates - external and internal, between which a vaginal cavity is formed around the testis - cavum vaginale. External parietal plate - lam. parietahs - is a continuation of the parietal peritoneum and lines the inner surface of the scrotal cavity. Between the last and peritoneal cavities there is a constant communication - the vaginal ring - anulus vaginalis. Internal visceral plate - lam. visceralis - closely associated with the membranes of the testis, its appendage and the vas deferens. Caudally, the vaginal membrane passes to the testis, forming the mesentery of the testis - mesorchium - a fold of the peritoneum containing the vessels and nerves of the testis.
Outside of the vaginal membrane is a striated muscle that lifts the testis - m. cremaster. It starts from the iliac fascia and is attached to the vaginal membrane near the testis; located between the outer seminal fascia - f. spermatica ext. (continuation of the fascia of the external oblique muscle of the abdomen) - and the internal seminal fascia - f. spermatica int., which is a continuation of the transverse fascia of the abdominal muscles. The fascia of the muscle that lifts the testis is closely connected with the muscle - f. cremasterica. The function of the muscle is to pull the testis into the abdominal cavity through the inguinal canal. The last fascia is covered with a layer of smooth muscle fibers in the subcutaneous tissue - the fleshy membrane (muscle) - tun. dartos (t.), which forms the median septum of the scrotum between the cavities of the scrotum. The outermost layer of the organ is the skin of the scrotum - cutis scroti, covered with wool.
Innervation - sexual branch n. genitofemoralis, scrotal branch of n. dors, penis. Blood supply - ventral scrotal branch a. profunda femoris, dorsal scrotal branch a. pudenda int.
The genital organs of the female - organa genitalia feminina - include the ovaries, fallopian tubes, uterus, vagina and vestibule.
Ovary - ovarium (Fig. 5) - a small paired ovoid organ; if present in it, the follicle acquires a grape-like shape. The mass of the ovaries during pregnancy and lactation is highly dependent on the number and size of the corpus luteum in them. In mature rats, the ovaries are located caudal to the kidneys and are surrounded by adipose tissue. The egg cells are microscopic, but small protruding vesicles are visible on the surface of the ovaries - vesicular ovarian follicles (Graafian vesicles) - folliculi ovarici vesiculosi (Graafi), each of which contains a cavity filled with fluid and increases as it matures. When the egg matures, the wall of the ovarian follicle ruptures and the egg enters the abdominal cavity; this stage of the ovarian cycle is called ovulation - ovulatio. Pregnant rats also have a noticeable corpus luteum - corp. luteum, which develops in the ovary after ovulation from the cells of the granular layer - str. granulosum - and connective tissue membrane of the follicle - follicle theca - theca folliculi; is an endocrine gland that secretes progesterone. After degeneration of the corpus luteum, a site of scar-degenerate ovarian tissue is formed in its place - a whitish body - corp. albicans.
On the section of the ovary, a peripheral zone is clearly visible, containing follicles - the cortex of the ovary - cortex ovarii, and the vascular part - the medulla of the ovary - medulla ovarii, starting from the gate of the ovary - hilus ovarii, the area of attachment of the mesentery of the ovary and the entry of vessels and nerves. The connective tissue supporting structure of the organ is called the ovarian stroma - stroma ovarii. The ovary is surrounded by a white dense albuginea -tun. albuginea; the wall is built from a cuboidal superficial epithelium - epitelium superficial, passing into a single-layer epithelium - mesothelium in the area of attachment of the mesentery of the ovary to the ovary. On the periphery of the organ there are many primary ovarian follicles - folliculi ovarici primarii; each consists of an immature female reproductive cell - an oocyte (oocyte), surrounded by one or more layers of follicular cells until a cavity filled with follicular fluid appears.
Rice. 5 Genitourinary system of the female (from the ventral side)
1 - gene, 2 - ovarium, 3 - cornu uteri sin., 4 - urethra feminina, 5 - gl. preputialis, 6 - rima pudendi (vulvae), 7 - glans clitoridis, 8 - vagina, 9 - vesica urinaria, 10 - tuba uterina, 11 - ureter.
The ovary has tubal and uterine ends. To the cranial tubal end - extremitas tubaria - is attached the funnel of the fallopian tube, to the caudal uterine end - extremitas uterina - the ovary's own ligament - lig. ovarii proprium; the latter is a bundle of connective tissue covered with peritoneum between the uterine end of the ovary and the top of the uterine horn or the adjacent mesentery of the uterus. To the dorsal mesenteric edge - margo mesovaricus - is attached the mesentery of the ovary - mesovarium, which is part of the broad ligament of the uterus; contains the vessels of the ovary and is a homologue of the mesentery of the testis. The ovary, together with the mesentery of the fallopian tube and the distal mesentery of the ovary, is part of the ovarian sac - bursa ovarica; the bag is deep, filled with fat and almost completely hides the ovary.
Innervation - pi. ovaricus; blood supply - ovarian branches a. ovarica.
Fallopian tube - tuba uterina (see Fig. 5), sometimes called the oviduct - oviductus, or fallopian tube (tuba Fallopi), - a thin curved tube, one end of which communicates with the cavity of the horn of the uterus, and the other, expanded - funnel of the fallopian tube - infundibulum tubae uterinae - opens into the peritoneal cavity at the surface of the ovary. Around the edge of the funnel, its mucosa is collected in folds - pipe fimbriae - fimbriae tubae, ovarian fimbriae - fimbriae ovarica - attached to the ovary. In the depths of the funnel is the abdominal opening of the fallopian tube - ost. abdominale tubae uterinae. Caudally, the tube opens into the cavity of the uterine horn with the uterine opening of the tube - ost. uterine tubae. The tube has its own mesentery of the fallopian tube - mesosalpinx, which is part of the wide ligament of the uterus. The mucous membrane of the fallopian tube is lined with ciliated epithelium and has tubal folds - plicae tubariae. The mucosa is followed by the muscularis, submucosa, and serosa.
The uterus - uterus (metra) (see Fig. 5) - consists of a body, two uterine horns and a cervix. In rats, the right and left uterine horns fuse with their lower ends at the level of the top of the bladder and open into the vagina, in fact, by separate openings of the uterus - ostia uteri. The horns and body of the uterus contain the uterine cavity - cavum uteri. The body of the uterus - corp. uteri - a small undivided part between the horns of the uterus and the cervix, located in the abdominal cavity dorsal to the bladder and ventral to the rectum. Craniolaterally from the body of the uterus to the right and left is a paired tubular, relatively long horn of the uterus (right and left) - cornu uteri (dext. et sin.). Each horn terminates cranially in a convoluted fallopian tube near the caudal end of the kidney. Cervix - cervix uteri - a small thick-walled area between the body of the uterus and the vagina; located dorsal to the bladder and is a pair of folds that close the walls and close the opening of the uterus.
Internal mucous membrane (endometrium) - tun. mucosa (endometrium) - the uterus has a thick glandular plate of its own and is lined with a cylindrical epithelium; contains branched tubular uterine glands - gll. uterinae. In the region of the cervix, the mucous membrane is collected in longitudinal folds - plicae longitudinales. Muscular membrane (myometrium) - tun. muscularis (myometrium) - consists of thick inner circular and oblique layers of smooth muscle fibers and an outer longitudinal layer associated with the serous membrane; the vascular layer separates the circular and longitudinal layers.
Serous membrane (perimetry) - tun. serosa (perimetrium) - covers the outside of the uterus, being its visceral peritoneum, and forms a wide ligament of the uterus - lig. latum uteri - a fold of the peritoneum that attaches the intraperitoneal genital organs of the female to the dorsolateral wall of the body. The broad ligament includes the merged mesentery of the ovary, fallopian tube and mesentery of the uterus - mesometrium. The round ligament of the uterus - lig. teres uteri, which extends from the cranial end of the uterine horn to the body wall; part of the lateral fold of the broad ligament of the uterus. Between the peritoneal sheets of the mesentery of the uterus is parametrium, parauterine fiber - parametrium, which includes connective tissue, smooth muscle, blood vessels and nerves.
Innervation - pl. uterovaginalis; blood supply - uterine and tubal branches a. ovarica, a. uterina.
The vagina - vagina (see Fig. 5) - is located mostly in the retroperitoneal space dorsal to the urethra and ventral to the rectum. There is a dorsal wall - paries dors., adjacent to the rectum, and a ventral wall - paries ventr., which is in contact with the urethra. The cervix protrudes into the cranial part of the vagina. Above it, the wall forms a blind pocket-like protrusion - the vaginal vault - fornix vaginae, surrounding the vaginal part (cervix) - portio vaginalis (cervicis). The mucous membrane is lined with stratified mucous epithelium and is collected in distinct longitudinal vaginal folds - rugae vagmales, does not contain glands. The muscular membrane consists of layers of smooth muscle fibers - inner circular and outer longitudinal; outside, the retroperitoneal part of the vagina is covered with a connective tissue adventitia membrane. The serous membrane is expressed only at the cranial end of the vagina. The entrance to the vagina - the opening of the vagina - ost. vaginae - limited in non-copulating females by a fold of mucous membrane - hymen - hymen, which usually exists for the first 10 weeks, that is, before puberty; the hymen is located cranial to the transverse plane through the external opening of the urethra. Caudally, the vagina passes into the vestibule of the vagina.
Innervation - nn. vaginales from pl. uterovaginalis; blood supply a. vaginalis, vaginal branches of a. profunda clitoridis.
The vestibule of the vagina - vestibulum vaginae - part of the female genital canal from hymen to the labia. In humans, the vestibule is so shallow that it is considered part of the external genitalia. In tetrapods, the deep location of the vestibule allows it to be attributed to the internal genital organs of the female. The urinary and genital tracts of the rat do not join at the vestibule and do not form the urogenital sinus, as, for example, in the cat. The mucous membrane of the vestibule is lined with stratified epithelium and contains multiple microscopic branched tubular small vestibular glands in the ventral and lateral walls - gll. vestibulares minores. In the lateral wall of the vestibule there is a paired vestibule bulb - bulbus vestibuli, which is a plexus of veins, cavernously dilated in places, covered with connective tissue with a small amount of smooth muscle cells.
External genital parts (organs) of the female - partes (organa) genitales femininae ext. - include the genital area of the female and the clitoris; the female urethra (female urethra) is also examined here.
The female genital area - pudendum femininum (vulva) (see Fig. 5) - is represented by the labia and their adhesions. The labia - labium pudendi (vulvae) - is a rounded fold of skin; in a rat, the large and small lips are indistinguishable. The outer surface of the lips is covered with skin with a small amount of hair, the inner surface has a mucous surface lined with stratified squamous epithelium. Ventral and dorsally, the lips are connected, respectively, by the ventral commissure of the lips - connnissura labiorum ventr. - and dorsal adhesion of the lips - commissura labiorum dors. The left and right lips laterally limit the entrance to the genital gap - riraa pudendi (vulvae). In the thickness of the labia there is a constrictor (compressor) of the vagina, consisting of striated muscle fibers. Between the ventral angle of the genital slit and the anus is the perineum.
Clitoris - clitoris (see Fig. 5) - a rudimentary analogue of the male penis, located cranial to the genital slit. Consists of legs, body and head. The leg of the clitoris - crus clitoridis - is paired, attached to the ischial arch and caudally forms the body of the clitoris - corp. clitoridis. The body consists of a paired cavernous body of the clitoris fused together - corp. cavernosum clitoridis. The head of the clitoris - glans clitoridis - is expanded from the outside, surrounded by a skin sac - the preputium (foreskin) of the clitoris - preputium (praeputium) clitoridis, into which modified sebaceous and sweat paired preputial glands - gll open. preputiales, similar to those of males. At the very tip of the head of the clitoris, the external opening of the urethra (urethra) opens.
The female urethra (female urethra) - urethra feminina (see Fig. 5) - corresponds to the part of the male urethra from the bladder to the prostate gland. It is a short tube located ventral to the vagina and running from the place where both ureters enter the bladder to the external opening of the urethra (urethra) - ost. urethrae ext., opening at the tip of the head of the clitoris. Outside, the canal is covered with a thin connective tissue adventitial membrane, followed by a smooth muscle membrane and, finally, a mucous membrane. Around the urethra is a layer of cavernous tissue - spongy layer - str. spongiosum.
Innervation of the external genitalia of the female: nn. labiales, n. dors, clitoridis, n. corp. cavernosiclitoridis. Blood supply - dorsal labial branch a. rectalis caud., a. clitoridis, a. dors, clitoridis, a profunda clitoridis, urethral branch of a. dors, clitoridis.
The perineum - perineum - is a collection of soft tissues of the body wall that covers the caudal opening of the pelvis and is located between the anus and the external genitalia; from the lateral sides it is limited by ischial tubercles. Muscles of the perineum - mm. perinei - include the diaphragm of the pelvis - diaphragma pelvis - the common name for the muscles (muscle that lifts the anus, coccygeal muscle) and fascia that form the bottom of the pelvis and a knot consisting of connective and muscle tissue between the anus and the genital area of the female or the bulb of the penis. This formation is similar to the tendon center of the perineal mu- centrum tendineum perinei (corp. perineale) - other animals; the external sphincter of the anus, the bulbous-spongy muscle, the muscle that lifts the anus, and the superficial transverse perineal muscle are attached to it.
The muscle that lifts the anus is m. levator ani - located lateral to the rectum and, as it were, covers it from two sides. On the ventral side, the muscle of each side is covered by a relatively large bulbospongius muscle, which is adjacent to the rectum. Medially, the levator ani muscle terminates at the external sphincter of the anus. Laterally and medially from the above muscle, respectively, are the outer and inner fascia of the pelvic diaphragm - fasciae diaphragmatis pelvis ext. et int.; the first - continues dorsally into the deep fascia of the tail, the second - caudally covers the rectum. Internal sphincter of the anus - m. sphincter ani int. - ribbon-like smooth muscle fibers that continue into the circular layer of the muscular membrane of the rectum. External anal sphincter - m. sphincter ani ext. - striated muscle surrounding the internal sphincter of the anus. The skin part - pars cutanea - is represented by thin bundles of fibers running dorsoventrally around the anus or diverging radially. Many bundles of fibers of the superficial part - pars superficialis - go through the ventral crossing into the muscle that compresses the genital gap, or end in the bulbous-spongy muscle in the male. The deep part - pars profunda - is closely connected or continues into the muscle that lifts the anus.
The perineal membrane - membrana perinei - is a deep fascia that covers the urogenital triangle between the ischial arch and the pelvic diaphragm. Attached to the urethra in the male or to the vestibule of the vagina between the muscle of the urethra and the bulbospongius muscle. Muscle of the urethra - m. urethralis - striated, covers the pelvic part of the urethra in the male between the prostate and bulbourethral glands; fibers have a circular direction and are partially attached to the legs of the penis. In females, the muscle starts from the sides of the vagina and forms a muscular band located ventral to the urethra.
The above muscles are common to males and females.
The following muscles are present only in the male.
Bulbous spongy muscle - m. bulbospongiosus, previously called the bulbous-cavernous muscle - m. bulbocavernosus, - relatively large, consists of two different parts; adjacent to the ventral surface of the levator ani muscle and to the lateral side of the rectum. It starts from the albuginea lateral to the spongy body of the penis; the body is compressed by means of a muscle that is attached in the region of the median septum of the penis. In females, this muscle corresponds to the constrictors of the vestibule and genital fissure. Ischiocavernosus muscle - m. ischiocavernosus - located lateroventral to the bulbous spongy muscle; originates from the ischial tuberosity, goes around and covers the bulbourethral gland and attaches to the body of the penis at the junction of its legs, surrounding the latter. In females, the muscle is underdeveloped, starting from the ischial arch.
The next two muscles are unique to the female.
Constrictor vestibule - m. constrictor vestibuli - a strong muscle that compresses the vestibule; located in its wall. It originates from the external sphincter of the anus and attaches to the aponeurosis connecting the left and right muscles, ventral to the vestibule; caudally passes into the constrictor of the genital fissure. Genital gap constrictor - m. constrictor vulvae - a ribbon-shaped striated muscle located in the labia; starts from the superficial part of the external sphincter of the anus and ends in the region of the labia. Together with the previous muscle, it corresponds to the bulbous-spongy muscle of the male.
Innervation of the perineum: n. perinealis; blood supply - muscular branches a. pudenda int., muscular branches of a. penis, a. profunda clitoridis.
The peritoneum - peritoneum (peritonaeum) - is a serous membrane lining the inside of the abdominal cavity, pelvic cavity and scrotum and covering the internal organs located in it; has a barrier function, the ability to secrete serous fluid and resorb liquids and suspensions. The peritoneum is a closed sac with parietal and visceral layers. Parietal, or parietal, peritoneum - peritoneum parietale - lines the walls of the abdominal cavity, pelvic cavity and scrotum; visceral, or visceral, peritoneum - peritoneum viscerale - covers the organs located in the cavities. On the dorsal wall of the abdominal cavity, the parietal peritoneum passes into the visceral. The set of slit-like spaces between the two layers of the peritoneum is called the peritoneal cavity, or the cavity of the peritoneum, - cavum peritonei; it contains a small amount of serous fluid, which facilitates the movement of organs in relation to each other and to the abdominal wall. Both parts of the peritoneum consist of a serous membrane, including a layer of mesothelium and a layer of connective tissue, and a serous base - a layer of loose connective tissue and fat, located under the serous membrane in certain areas of the peritoneum.
The abdominal cavity - cavum abdominis - is the space containing the internal organs, with the exception of the heart, lungs and kidneys. From the inside, the cavity is lined with the parietal peritoneum and filled with serous fluid, similar in shape to a compressed ovoid. Dorsally, the wall of the cavity is bounded by the lumbar part of the spine, the psoas major, the latissimus dorsi, and the quadratus lumborum; ventrally - rectus muscles and aponeuroses of the oblique and transverse muscles of the abdomen, from the sides - parts of the costal walls, sections of the diaphragm, the abdominal wall. Cranially, the cavity is limited by the diaphragm, caudally, it passes into the pelvic cavity. In males, the abdominal cavity communicates with the scrotal cavity through the inguinal canal; in females, it communicates with the external environment through the fallopian tubes, uterus and vagina.
Pelvic cavity - cavum pelvis - the space between the cranial and caudal apertures of the pelvis; has a funnel-shaped shape with a wide base directed towards the abdominal cavity. The walls of the cavity are formed by the pelvic bones, ligaments of the sacroiliac joint, the ventral surface of the sacrum, and the bodies of the caudal vertebrae. In the pelvic cavity from the abdominal cavity comes the fascia, which here is called the pelvic fascia - f. pelvis. It is subdivided into the parietal fascia of the pelvis - f. pelvis parietalis, lining the walls of the cavity (includes the obturator fascia - f. obturatoria - and the internal fascia of the pelvic diaphragm) and the visceral fascia of the pelvis - f. pelvis visceralis, which forms the membranes for the pelvic organs.
From the dorsal wall of the abdominal and pelvic cavities, the mesentery descends to the internal organs. The mesentery - mesenterium - is a fold of the peritoneum, with the help of which the intraperitoneal organs are attached to the walls of the abdominal and pelvic cavities. According to the place of attachment of the intestinal tube in the embryo, the ventral (abdominal) mesentery - mesenterium ventr is distinguished. - and dorsal (dorsal) mesentery - mesenterium dors. In the process of development, the ventral mesentery disappears almost along the entire length of the intestinal tube, remaining only on the stomach, where the lesser omentum and ligaments of the liver are formed from it. The greater omentum, mesentery of the small intestine, colon, etc. develop from the dorsal mesentery. Each section of the intestine has its own mesentery.
The mesentery of the duodenum - mesoduodenum - is short, in the form of a ligament. The mesentery, attached to the jejunum and ileum, is designated as the mesentery of the small intestine - niesenterium; it is long, like the mesentery of the colon - mesocolon. The mesentery of the rectum - mesorectum - narrow, short. The mesentery of the stomach is the omentum. The embryo has a ventral mesentery of the stomach - mesogastrium ventr., Connecting the stomach to the ventral abdominal wall. During maturation, the developing liver divides the mesentery into hepatic ligaments and omentum. In an adult animal, the lesser omentum - omentum minus - is a duplication of the peritoneum, connecting the lesser curvature of the stomach and the cranial part of the duodenum with the visceral surface of the liver. Ligaments come from these organs: hepatogastric - lig. hepatogastricum, the main part of the lesser omentum and hepatoduodenal - lig. hepatoduodenale; the latter is the free right edge of the lesser omentum. It connects the liver to the cranial part of the duodenum, contains the portal vein, hepatic artery, common bile duct and forms the ventral border of the omental opening. The greater omentum - omentum majus (epiploon) - is a peritoneal sac, a duplication of the peritoneum, located between the intestines and the ventral abdominal wall and surrounding the cavity - the caudal omental recess - recessus caud. omentalis. The omentum descends from the greater curvature of the stomach, covers the loops of the small intestine and fuses with the transverse colon. The part of the greater omentum between the stomach and the spleen is called the gastrosplenic ligament - lig. gastrolienale. There is also a stuffing bag - bursa omentalis - part of the peritoneal cavity, a small peritoneal sac, a space limited by two omentums, a stomach and a liver. The part of the bag limited by the lesser omentum, stomach and liver is called the vestibule of the stuffing bag - vestibulum bursa omentalis. Stuffing hole -- for. omentale (epiploicum) - connects the large peritoneal sac with the vestibule of the stuffing bag; it passes between the caudal vena cava and the portal vein.
The cranial part of the pelvic cavity is lined with the parietal peritoneum, which, when moving from the wall to the internal organs, forms folds. To the dorsolateral wall of the body from the intraperitoneal genital organs of the female is a fold of the peritoneum - a wide ligament of the uterus. In males, the genital fold - plica genitalis - separates the recto-genital recess from the vesico-genital cavity and contains the vas deferens. From the dorsolateral walls of the pelvis to the bladder go the folds of the peritoneum - the lateral ligaments of the bladder, and the unpaired median ligament of the bladder is attached to the ventral surface of the bladder. Between the pelvic organs and the folds of the peritoneum are unpaired cavities, indentations. The pocket of the peritoneal cavity between the rectum and the genital fold (in the male), the rectum and the uterus with its wide ligaments (in the female) is called the recto-genital recess - excavatio rectogenitalis. Another space - the vesico-genital recess - excavatio vesicogenitalis - is located in males between the bladder and genital fold, in females - between the bladder and uterus with wide ligaments.
The organs of the abdominal cavity are divided into those covered with peritoneum on all sides (small intestine), free from the peritoneum on one side (part of the rectum) and only bordering on the peritoneal sac. The latter are called retroperitoneal organs - organa retroperitoneale; these include the kidneys and adrenal glands. They are located in the retroperitoneal (retroperitoneal) space - spatium retroperitoneale, which is a part of the abdominal cavity located between the parietal peritoneum and intra-abdominal fascia and extending from the diaphragm to the pelvis; filled with loose connective and adipose tissue with organs, vessels, nerves and lymphatics located in them.
In adult animals, the abdominal cavity is connected to neighboring cavities with holes. The openings of the esophagus, caudal vena cava and aorta are located in the diaphragm and lead to the chest cavity. The inguinal openings in males open into the inguinal canals and cavities of the scrotum. The abdominal cavity in females communicates with the external environment through the fallopian tubes and uterus. The embryo also has a hole in the middle of the white line of the belly - the umbilical ring - anulus umbilicalis, through which the umbilical cord passes, and after birth it is filled with its obliterated remnants. The umbilical cord (umbilical cord) - funiculus umbilicalis (Fig. 6) - is a dense cord connecting the body of the embryo with the placenta; contains blood vessels, yolk duct, allantois duct. When the tissues are scarred at the place where the umbilical cord falls off, an umbilicus is formed - a depression in the middle part of the abdominal wall.
Rice. 6 Rat embryo in embryonic membranes
1 - amnion, 2 - funiculus umbilicalis, 3 - placenta.
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Raise the xiphoid process of the sternum with tweezers, open the chest cavity; to do this, using scissors and a scalpel, make oblique incisions starting from the lower lateral corners of the chest cavity, through the ribs and muscles towards the neck, and remove the anterior chest wall.
In the chest cavity, locate the heart in the pericardial sac and pale pink lungs with bronchi and trachea. The esophagus is located behind and to the side of the trachea.
The rat digestive system is more complex than that of amphibians and reptiles. It begins with the mouth opening, which is surrounded by lips. AT oral cavity food is crushed by the teeth (compare with the teeth of amphibians and reptiles) and wetted by saliva secreted by the salivary glands. Food enters the stomach through the pharynx and esophagus. Note that the esophagus perforates the diaphragm and passes into the stomach, located below the diaphragm. To examine the intestines, you should cut the mesentery with scissors, unravel the loops of the intestines and straighten it along the bottom of the bath or on a board, next to the body of the animal. Locate the duodenum, branching off from the stomach; the ducts of the liver and pancreas flow into it. Find a large friable pancreas lying in a loop of the duodenum. The rat does not have a gallbladder. Note that the duodenum, without a sharp border, passes into the small intestine, which in turn continues into the large intestine. Locate the caecum, ending in the blind process (appendix). It is located where the small intestine merges into the large intestine. The cecum of the rat is large. The final section of the large intestine, gradually narrowing, passes into the rectum, ending in the anus. The total length of the entire intestine of the rat is 5-6 times the length of the body.
The respiratory organs are more differentiated than in reptiles. Locate the trachea, which begins with the larynx, formed by cartilages: cricoid, thyroid, epiglottis and two arytenoids. Locate the thyroid gland on the sides of the trachea, which lies on the thyroid cartilage and consists of two halves connected to each other. Pulling the trachea forward with tweezers, find the place where it divides into two bronchi. In the lungs, the bronchi branch strongly. Cut the trachea at the top, insert a glass tube into it and inflate the lungs with air. On inflated lungs, their cellular structure is clearly visible. Consider the shell that covers each lung from the outside - the pleura; she also covers inner wall chest cavity. Note that the lungs are permeated with a network of blood capillaries. The strong development of the lungs and the presence of the diaphragm provide more perfect breathing than in amphibians and reptiles. Lift with tweezers and incise the pericardial sac (pericardium). Examine the heart - it is apex backward, two dark red atria are well distinguished from the pale pink ventricles, directed backward and forming the apex of the heart. Consider the vessels leaving the heart - the aortic arch with arteries branching from it and the pulmonary artery. Carefully cut the vessels, remove the heart from the pericardium, which is removed along with the thymus gland, similar to a fatty formation (the thymus gland is highly developed in young animals).
Take your heart in your left hand right hand with a scalpel, make an incision in the walls of the left atrium and ventricle, and then incision in the right atrium and ventricle: atria - thin-walled ventricles have thick muscular walls. Insert the forceps into the cavity of the left and right ventricles, compare the thickness of their walls. The wall of the left ventricle, which gives impetus to the movement of blood through the systemic circulation, is much thicker than the wall of the right one. Please note that the right half of the heart, containing venous blood, is completely isolated from the left - arterial.
Follow the path of blood through the systemic and pulmonary circulations on the injected drug and the blood circulation scheme (Figure 79). The pulmonary circulation begins from the right ventricle with the pulmonary artery. Soon after exiting the heart, it branches into the right and left pulmonary arteries, which carry venous blood to the lungs. Gas exchange takes place in the capillaries of the lungs. Then, through the pulmonary veins, arterial blood enters the left atrium and flows through its systole into the left ventricle, from where it is directed through the systemic circulation. With the contraction of the left ventricle, it flows into the aorta, which gives a sharp bend to the left. Unlike birds, which have a right aortic arch, mammals retain a left aortic arch. Three vessels depart from the aortic arch: a short innominate artery, which divides into the right subclavian artery and the right carotid artery, the left carotid artery and the left subclavian artery.
1 - atrium; 2 - ventricles; 3 - left aortic arch; 4 - nameless artery; 5 - left subclavian artery; 6 - right subclavian artery; 7 - carotid arteries; 8 - dorsal aorta; 9 - splanchnic artery; 10 - anterior mesenteric artery; 11 - renal artery; 12 - posterior mesenteric artery; 13 - genital artery; 14 - iliac artery; 15 - tail artery; 16 - anterior vena cava; 17 - jugular veins; 18 - subclavian veins; 19 - tail vein; 20 - iliac vein; 21 - mesenteric vein; 22 - portal system of the liver; 23 - hepatic vein; 24 - posterior vena cava; 25 - pulmonary artery; 26 - pulmonary
vein; 27 - unpaired vein. Vessels with venous blood are painted black
Figure 79 - Scheme of the circulatory system of the rat
Having rounded the heart, the aorta passes back along the spine. Vessels that carry blood to the internal organs depart from the aorta: intestines, liver, kidneys and other organs. In the pelvic cavity, the aorta splits into common iliac arteries, passing further into the lower extremities and supplying them with blood. Through a dense network of blood vessels, arterial blood delivers oxygen to the tissue cells of the animal's body. Venous blood collected from the whole body flows into the right atrium through the vena cava: from the front of the body through the paired anterior vena cava, and from the back of the body through the unpaired posterior vena cava. Venous blood from the intestine flows into the portal vein, which enters the liver and forms the portal system of the liver. In the liver, the capillaries join to form two hepatic veins, which empty near the heart into the posterior vena cava, which collects blood from the entire back of the body.
Find paired kidneys - they are located asymmetrically on the sides then the spine: the right kidney is higher than the left one. The kidneys of the rat are secondary, like the kidneys of reptiles and birds. Examine the ureters, which extend from the inside of the kidneys: they look like whitish threads, they go into the bladder. The bladder opens outward through the urethra (Figure 80).
Locate the female's two ovaries in the lumbar region near the kidneys, on the dorsal wall of the body cavity. Consider the oviducts - highly convoluted tubes that do not have a direct connection with the ovaries: one end of the oviduct, starting with a funnel that covers the ovary, is located near the ovary and faces the abdominal cavity of the body, the other opens into the uterus.
Note that the uterus consists of two horns that serve as a continuation of the oviducts. In the horns of the uterus, the embryonic development of the embryos takes place. Find an unpaired vagina, into which the horns of the uterus come off; the vagina opens outward through the genital opening.
Find the testicles of a male rat - they are in the scrotum - a special bag at the base of the tail, representing a protrusion of the body wall. If they are not visible, press lightly on the scrotum with your fingers and push the testicles into the body cavity. Examine the appendages adjacent to the testes - the epididymis and the vas deferens extending from them. Note the adnexal gonads in the body cavity, the highly branched seminal vesicles (near the bladder), and the multilobular prostate at the bladder neck. The vas deferens take in the ducts of these glands and flow into the urethra. 
1 - testis; 2 - appendage of the testis; 3 - seed tube; 4 - seminal vesicles; 5 - prostate gland; 6 - bladder; 7 - ureter; 8 - kidney; 9 - scrotum; 10 - inguinal canal; 11 - ovary; 12 - fallopian tube; 13 - uterus; fourteen -
vagina
Figure 80 - Urogenital organs of male (I) and female (II) rats
The study of the brain of a rat is carried out by opening the skull or on a ready-made wet preparation. To open the skull, cut off the head of the rat with a section of the neck. Remove the skin from the rat's head. After cutting the skull bones with scissors, remove them with tweezers and clear the cranial cavity so that the brain is clearly visible from above. Consider the small olfactory lobes - behind them are the forebrain hemispheres (large hemispheres of the brain). Note that the hemispheres are covered with gray matter that forms the cerebral cortex. The diencephalon is not visible from above - it is closed by the hemispheres, relatively small and located between the posterior edge of the cerebral hemispheres and the cerebellum. Consider the midbrain - it is almost completely covered by the hemispheres of the forebrain. The cerebellum is very strongly developed and almost covers the medulla oblongata (Figure 81). The sense organs of the rat are well developed.
1 - olfactory lobes; 2 - hemispheres of the forebrain; 3 - midbrain; 4 -
cerebellum; 5 - medulla oblongata; 6 - rhomboid fossa; 7 - spinal cord
Figure 81 - Rat brain from above
The strong development of the brain and sense organs determines the more complex behavior of mammals compared to other vertebrates. Draw the brain of a rat from above, Cut through the olfactory lobes and tilt the brain back with the end of the scalpel so as to expose its lower surface.
Questions for self-control:
1. What is the difference between mammals and reptiles and birds?
2. What are the advantages of placental mammals and how did this affect their distribution?
3. Name the skin glands of animals.
4. What is the structure and role of the hairline?
5. What is the origin of claws, hair, horns, hooves?
6. What is the diaphragm and what is its role?
7. What are the progressive features of the structure of the circulatory system of mammals expressed in?
8. What structural features of the brain are characteristic of animals?
9. What is fertilization in mammals? Where does the egg develop?
10. What are the functions of the germinal membranes?
11. What is the type of development in young mammals? Where do juveniles develop?
The basis of the study is the independent study by the student of all educational material.
At independent work over the course the student uses textbook material. The study should be carried out sequentially, in the order in which the material is presented in the book, which approximately corresponds to the course of the process of the historical development of the animal world.
According to the program, it is necessary to study all the textbook material without exception, but the degree of detailing the assimilation of its individual sections should be to a certain extent selective.
METHODOLOGICAL ADVICE ON STUDYING SELECTED TOPICS AND QUESTIONS FOR INDEPENDENT VERIFICATION OF KNOWLEDGE
The study of the factual material is carried out according to special chapters of the textbook.
MAIN TYPES OF ANIMAL WORLD
Subkingdom Onocellular, or Protozoa
Type Sarcomastigophora
Type Apicomplexes
Type Myxosporidium
Type of microsporidia
Type Ciliates, or Ciliary
Subkingdom Multicellular animals
Sponge Type
Type Intestinal
Type Ctenophora
Type Flatworms
Type Round, or Primary worms
Type of Nemertine
Type Annelids
Type Shellfish
Type Arthropods
Type Echinoderm
Type Tentacled
Type Chordates
Below is a list of the main topics for individual zoological groups, where the content is indicated, as well as questions that should be used for repetition, self-examination.
INTRODUCTION
The role of animal taxonomy in understanding the evolution of the animal world and in solving national economic problems. The concept of type, class, detachment, family. Principles of classification, binary nomenclature.
The main types of animals. Number of known animal species of different types and classes. The role of Russian scientists c. development of zoology and its successes.
Questions for self-examination
1. The subject of zoology and its place in the system of other natural sciences.
10. What is the practical significance and role of zoology in the protection, transformation of nature and in the development of agriculture?
PROTOTIAS
Characteristics of the subkingdom of protozoa. Division into main types and classes:
Sarcode. The structure, nutrition, reproduction and lifestyle of Amoeba. Foraminifera, rays and their significance.
Microsporidia as causative agents of nosematoses - diseases of bees. Disease prevention and control.
Evolution of the simplest. The rate of reproduction of protozoa, their importance in the circulation of substances in various habitats. The role of Russian scientists in the study of protozoa.
Questions for self-examination
The cell as an organism in protozoa and the cell as part of the whole organism in multicellular organisms. The cell is the basic element of life. Chemical and physiological properties of cells. Communication between unicellular and multicellular animals. The main methods of reproduction in multicellular organisms. Fertilization. Nuclear and cell division. The main patterns of crushing a fertilized egg; morula, blastula, gastrula stages. Germinal leaves. Theories of the origin of multicellular animals (Haeckel, Mechnikov).
SPONGE
Sponges, their structure, nutrition and reproduction. The value of ontogenesis in understanding the origin (phylogeny) of sponges.
COELENTERATES
The main classes, structure, nutrition and reproduction. Radial symmetry in the organization of coelenterates in relation to lifestyle. Metagenesis in hydroid and scyphoid polyps. The significance of movement in the origin of the muscular and nervous systems with sense organs in jellyfish. Coral polyps, distribution and biological significance. Phylogeny of coelenterates.
ctenophores
Characteristics of the type (development, growth, structure, fertilization).
Questions for self-examination
1. Describe coelenterates as multicellular animals.
General characteristics and division into main classes.
Eyelash worms. Morphology and phylogeny of ciliary worms. The origin of bilateral (bilateral) symmetry in the organization of worms and its significance in the evolution of animals.
Flukes (trematodes). Reproduction, development with alternation of generations and change of owners. Correlation between ontogeny and phylogeny in flukes. The main representatives of trematodes, the cycles of their development and the diseases they cause in domestic animals and humans. Fight against flukes.
Tapeworms (cestodes). Their structure, reproduction and development (ontogenesis), fertility. Tapeworms and tapeworms, their most important representatives and development cycles. Tapeworms as causative agents of parasitic diseases in animals and humans. Fight against cestodes. Significance of the works of K. I. Scriabin and others.
An autopsy of a rat can be carried out either in large baths or on special dissecting boards, in this case tying the animals by their paws to four nails driven in at the corners. The wool on the ventral side is moistened with water and smoothed into the middle; after that, a longitudinal skin incision is made along the parting line.
The skin is easily separated from the muscle layer, and it only needs to be cut slightly with a scalpel; its flaps are pulled to the sides and fixed with pins on the wax bottom of the bath or on a dissecting plate (Fig. 285).
First of all, the abdominal cavity is opened and its muscular walls are also pulled to the sides and fixed with pins. To open the chest cavity, it is necessary to cut the ribs and the shoulder girdle on the sides (both cuts must converge at the base of the neck). After that, the anterior wall of the chest cavity should be removed along with the sternum and segments of the ribs; in the process of this work, we will find a diaphragm, which should be gradually and carefully separated from the walls of the body and kept on the preparation.
The diaphragm is a transverse muscular septum that separates the chest cavity from the abdominal cavity. In a relaxed state, it looks like a bowl, which protrudes into the chest cavity with its convex side; when muscle fibers contract, it stretches, and as a result, the capacity of the chest cavity increases (for the significance of diaphragm contractions during breathing in mammals, see below). The presence of the diaphragm is salient feature mammals.
When the general picture of the internal structure opens before us, we can easily recognize the dark red liver located in the abdominal cavity under the very diaphragm, which partly covers the pear-shaped stomach, and then the voluminous mass of intestines, covered on the outside by a fold of the peritoneum - the omentum (as the name shows , here, in well-fed animals, reserves of fat, that is, animal fat, are deposited).
If we opened not a rat, but a rabbit, then, turning away the right lobe of the liver, we would see a yellowish gallbladder under it; however, in a rat, unlike most other mammals (including its related mouse), there is no gallbladder and bile from the liver is directly directed through the corresponding duct into the duodenum.
Near the left (from us - right) edge of the stomach, lower than it, we will find an oblong red spleen (remember the meaning of this organ).
To understand other organs of the abdominal cavity, which lie deeper, you need to pull out the entire lump of intestines and throw it back on the left side of the drug (still without starting to unravel it). At the bottom of the opened cavity, on the sides of the translucent spine, we will see a pair of dark red buds with characteristic shape beans (pay attention to their asymmetrical position - the left one is pushed back a little by the stomach).
Less visible are the adrenal glands adjacent to the anterior edge of each kidney (this is an endocrine organ).
From both kidneys, the ureters go back, which flow into the bladder in the lower abdomen (try not to pierce it).
The reproductive organs are also located near the bladder: two small testes in males and sac-like formations of a more complex structure in females.
We will dwell on the structure of the genital organs in more detail later - in the section on the reproduction of mammals; meanwhile, we note that in rats and other rodents it is not so easy to distinguish females from males by appearance. It should be remembered that in females, behind the convex genital tubercle, there are two openings - genital and anal, while in males in the corresponding place you can find only one opening - anal.
Continuing to consider the internal organs of the rat, we will find at the bottom of the abdominal cavity and the main blood vessels. The inferior vena cava is visible, carrying blood from the posterior half of the body to the heart and giving branches to the kidneys. The aorta, which is less visible here, lies somewhat deeper. At the level of the bladder, both the vein and the aorta split into two branches that go to the hind limbs.
In the chest cavity we will see a couple color pink lungs and between them the heart with large vessels extending from it. A cartilaginous trachea runs in front of the lungs, which then divides into two bronchi.
We note that the lungs in mammals do not adhere to the walls of the chest, but hang freely on the bronchi (and in birds?). Deeper than all these organs is the esophagus, which runs from the pharynx, pierces the diaphragm and flows into the stomach behind it.
Pulling the heart back, you can see the beginning of thick arterial trunks extending from its upper part. Here we find the arch of the aorta, which (unlike birds) bends to the left side (away from us to the right); this means that of the pair of arterial arches found in reptiles, mammals have lost the right arch and retained only the left, which carries arterial blood (but what about birds?).
As a result, in mammals, as in birds, only arterial, oxygenated blood enters the aorta.
From the aortic arch depart arteries that supply blood to the head (carotid) and forelimbs (subclavian); we saw the continuation of the arterial trunk at the bottom of the abdominal cavity.
Next to the aorta, but already from the right ventricle, the pulmonary artery begins, which soon splits into two vessels and carries venous blood to the right and left lungs. Already arterial blood comes back from the lungs, and the pulmonary veins bring it to the left atrium.
Throwing the heart back with a thin end up, we will notice on its reverse side the end of the inferior vena cava, which brings blood from the posterior half of the body to the right atrium.
Having understood these vessels, we can cut them, take out the heart, rinse it with water and examine it from all sides.
If we were dealing with a larger animal (at least with a rabbit), then the heart would have to be opened, making cuts as shown in Figure 286, and examining its walls, internal partitions and valves; however, on the small heart of a rat, such work, which requires skillful hands, is more difficult to do, and here, probably, one will have to confine oneself to a transverse section of the heart. Such a cut will show that the left and right ventricles are not equally developed, and will help to comprehend the difference between them in connection with the work performed by one and the other ventricle.
The complete (as in birds) separation of arterial and venous blood and the complex structure of the lungs, formed by countless pulmonary vesicles entangled in a network of capillaries (remember the sac-like lungs of frogs), contribute to increased gas exchange, which is also associated with the warm-bloodedness of mammals.
Features of the respiratory mechanism in mammals are associated with two features in their structure:
Then atmospheric pressure drives through the respiratory tract outside air into the lungs, and the lungs swell to fill the expanded chest cavity. This is how inhalation happens. When exhaling, the descending ribs and the diaphragm taking its previous position compress the lungs and force the air out of them back. We can easily trace these respiratory movements on ourselves (why does the abdominal wall protrude when the diaphragm contracts?).
