Team Members: ______
Group Name: ______
Cat Dissection: Urinary/Reproductive System Review
Objective: Identify & compare the gross anatomy of the cat’s urinary & reproductive systems to that of a human’s.
Materials: The following materials should be used:
1. Embalmed cat in plastic bag & dissection tray
2. Dissecting tools (heavy duty scissors, scalpel, probe, 2 dissecting needles, forceps)
3. Name tags & String
4. Latex surgical gloves
Proceedure:
The close association of the urinary & reproductive organs necessitates the study of the organs of these two systems together.
1. To expose the urogenital system, remove the liver, spleen, & stomach.
2. Identify the kidneys; they will be found embedded in fat on the dorsal body wall. The kidneys are not suspended by a mesentery as are the other abdominal organs & they are covered by peritoneum (which is the serous membrane lining the walls of the abdominal & pelvic cavities) only on the portion adjacent to the abdominal cavity. Because of this fact, the kidneys are said to be retroperitoneal.
3. With forceps & scalpel remove some of the excess fat around the kidneys but be careful not to destroy the adrenal gland, reproductive organs & blood vessels which are also embedded in fat in this region. Note that the left kidney is slightly caudad of the right one.
4. Identify the Hilus, the medial concave opening to the kidney, permitting access by the renal blood vessels & ureters.
5. Identify the 2 adrenal glands, which are embedded in connective tissue between the anterior ends of the kidneys & the large abdominal blood vessels (aorta & inferior vena cava).
6. Trace the ureter of each kidney to the bladder where it enters the dorsal surface of the bladder.
7. Identify the urinary bladder. Note that the bladder is also retroperitoneal. It is a musculomembranous sac attached to the abdominopelvic walls by ligaments formed from folds of peritoneum. The bladder is held to the ventral body wall by a medial ligament.
8. Identify the urethra, the duct extending from the neck of the bladder to the exterior. In the male, this duct extends through the penis & receives the male sex products. In the female, the duct opens to the vestibule inside the urogenital orifice.
Male Reproductive System
The genital area of the cat has not yet been skinned, do it now. Remove the skin cover the testes & the urogenital sinus area. The skin covering the testis forms the scrotal sac or scrotum. During embryonic development the testes descend from the region in the abdominal cavity where they originally develop, through the abdominal wall & into the scrotal sac. The main reproductive duct leading away from the testis is the vas deferens.
Locate the following structures which are underlined:
1. Scrotum, a large sack of skin, muscle & connective tissue on the exterior of the body just ventral to the anus & containing the testes.
2. Cut open the scrotum & note the following layers from the exterior to the inner wall: (1) integument;
(2) cremaster muscle & fascia; (3) tunica vaginalis.
3. To see the Testes more clearly, remove the tough layer of tissue which surrounds it. The testes are the paired reproductive glands within the tunica vaginalis that contain the seminiferous tubules (which are microscopic tubules within the testes where the spermatozoa are formed). Lying on the side of the testes, running the length of the organ is the epididymis
4. The epididymis, a highly coiled tubule connecting the vas efferentia & vas deferens (spermatozoa leave the epididymis through the vas deferens). The epididymis is where immature sperm are stored after they leave the testis.
5. Using a scalpel, cut through the muscle in the midline between the legs. If you are exactly at the midpoint, your scalpel blade will sink into the cartilage of the symphysis. Cut through the symphysis enough to weaken it, then place your hands on both legs & force them apart, breaking the joint & revealing the area posterior to the urinary bladder.
6. Clear away all connective tissue & trace the entire length of the urethra.
7. Vas deferens & blood vessels pass through the abdominal wall via the inguinal canal. From the inguinal canal the vas deferens passes up over the ureter & enters the penis near the prostate gland.
8. At the point of entry of the vas deferens into the urethra, there is a large, hard mass of tissue surrounding the urethra. This is the prostate gland. Prostate glands are small bulb-shaped glands covered by striated muscles & located where the vas deferens joins the urethra.
9. About an inch further down the urethra there are paired hard masses, the bulbourethral glands or Cowper’s glands. The prostate & Cowper’s glands secrete semen directly into the urethra. The cat does not have seminal vesicles, which are a third set of associated reproductive glands present in the human.
10. Locate the penis. The skin that forms the sheath around the organ is called the prepuce. Pull back the prepuce to expose the enlarged end, which is the glans. The glans in the cat is covered with minute horny papillae.
Female Reproductive System
The cat has a bicornuate uterus, that is, the organ has 2 large extensions (uteruses), whereas the human has only one uterine sac.
Locate the following underlined structures:
1. Ovaries. Identify the small, light colored oval ovaries which lie posterior to the kidneys. The ovaries are the female reproductive glands. The eggs develop by meiotic division inside fluid filled chambers called follicles. The follicles increase in size as the egg develops until it reaches the mature stage. The mature follicle is known as a Graafian follicle. After the egg erupts, the walls of the follicle become the corpus luteum. Eventually the corpus luteum degenerates into a corpus albicans (white body). The corpus luteum produces female sex hormones. Note, that the ovaries are held by a fold of tissue to the dorsal body wall. This peritoneal fold is called the mesovarium. Note also, that the ovary is attached to the uterine horn by the ovarian ligament.
2. The body of the uterus is located dorsal to the urinary bladder. The uterus’ (womb’s) function is to receive, retain, & nourish a fertilized egg.
3 Identify the uterine tube or fallopian tubes with its enlarged funnel like terminus, the infundibulum (abdominal ostium). Note that the perimeter of the infundibulum has many irregular projections called fimbriae. When the egg leaves the ovary they are drawn into the uterine tube through the infundibulum by ciliated epithelium on the tissues of the area.
4. From that point trace the paired uterine horns anteriorly. Notice that the uterus is Y-shaped, having 2 horns & a body. The uterine horns are very small in an immature female & large in a mature cat. In the case of the pregnant cat, the horns will contain embryos. At the anterior end of each uterine horn is the small, oval ovary, surrounded by the expanded end of the oviduct. The coiled oviducts may be seen lateral to the ovary & connecting with the uterine horn. The opening of the oviduct, which only partially surrounds the ovary is called the ostium.
5. To see the posterior end of the reproductive & urinary systems, follow the instructions given for the male reproductive tract & split the pubic symphysis. Trace the body of the uterus posteriorly as it passes dorsal to the urethra from the urinary bladder.
6. It terminates in the vagina, which opens to the vestibule or urogenital sinus.
7. If the cat has large uterine horns or is pregnant, cut into the vagina from the urogenital sinus opening craniad until you reach the cervix of the uterus. Make your cut to one side so as not to damage the urethra which, in the female cat, opens into the urogenital sinus in the midventral line. Look for a developing fetus.
Question: / Answers:1. What sex is your specimen?
2. What is the function of the ureters?
3. What is the function of the urethra?
4. In the male, where is immature sperm kept after it leaves the testes?
5. In the male, what are the names of the 2 glands that secrete semen directly into the urethra?
6. In the female, what is another name for the uterus?
7. In the female, what is a follicle?
8. The urethera is longer in which sex, male or female.
9. What is the function of the liver? (give @ least 4)
10. The kidneys & bladder are located in the abdominal cavity & are said to be ___ to the stomach.
11. Name the 4 major organs of the urinary system.
12. What is the name of the dark colored tissue inside the kidney?
13. What is the medial curvature of the kidney called?
14. What is the light colored tissue inside the kidney called?
15. The vas deferens is found in what sex of a mammal?
16. The glans of the male cat is covered with tiny what?
17. The corpus luteum is found in what sex mammal?
18. What is another name for the fallopian tube?
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