Urogenital Apparatus: Urinary & Female Anatomy

Urogenital Apparatus

• Study notes on the urinary and female reproductive viscera.
• Associate structure with function.

Learning Objectives

• Describe the topography, external and internal features of the kidneys.
• Identify the segments of the urinary tract in the order urine passes through them.
• Describe the topography, external and internal features of the urinary bladder.
• Describe the topography and length of the urethra dependent on sex and identify it.
• Describe the female gonads (ovaries) in terms of topography and structure.
• Identify the uterine tube, describing its relationship to the ovary and uterine horn.
• Describe and identify the main segments of the uterus, including their topography and internal features.
• Identify the vagina, vestibule, and vulva, while describing their topography and features.
• List and identify the main zones of the placenta in the bitch.
• Describe the total number and placement of mammary glands in the bitch.

Overview: Urinary Viscera

• Key components of the urinary tract include the kidneys, ureters, urinary bladder, and urethra.

Kidneys: Location

• Located in the lumbar region, attached to the ceiling of the abdominal cavity.
• Covered ventrally by the peritoneum (serous membrane).
• Surrounded by fat.

Kidneys: Role

• Function to filter plasma
• Endocrine functions include renin and erythropoietin production.

Kidneys: External Features

• Bean shaped
• Hilus, the indented area where vessels enter/exit, is medially oriented.

Kidneys: Structure

• Consists of the cortex and medulla.
• Medulla contains renal pyramids and renal crest.
• Also includes renal sinus and renal pelvis (collects urine from the renal crest) which leads to the ureter.

Ureters

• Drain urine from the kidneys.
• Emerge from the hilus of the kidney
• Run caudally to the dorsal aspect of the urinary bladder.
• Pass through the bladder wall at an oblique angle.
• Compression occurs if intravesical pressure rises.

Urinary Bladder

• Deposits urine between micturitions.
• Its position varies with plenitude, found on the floor of the abdomen or pelvic inlet.
• Features include the apex, body, and neck.
• Contains no visible sphincter, but the urethral muscle keeps the urethra constricted.

Urinary Bladder: Structure

• The adventitia is the bladder's outer layer, followed by the detrusor muscle(smooth muscle, under involuntary control)
• Mucosa contains a special impermeable lining, the urothelium, for no reasorbsorption/excretion processes.

Urethra: Female

• Short and located in the pelvic region only.
• Runs caudally in the pelvic cavity and opens at the junction of the vagina and vestibule.

Urethra: Male

• Longer, with two segments: pelvic and penile.
• The pelvic segment receives ducti deferentes.
• The penile segment resides inside the penis.

Overview: Female Reproductive Viscera

• Key components of the female reproductive system include: Ovaries, uterine tube, uterus with cervix, vagina, vestibule, and vulva.
• Ovaries are the female gonads.

Ovaries

• Topographically, they are located in the dorsal abdomen within the lumbar region.
• They are close to the tips of the uterine horns.
• Attached to the abdominal wall and uterus via ligaments, enclosed in the ovarian bursa.
• Play a role in female gametogenesis.
• Function as an endocrine organ, producing estrogen, progesterone, and testosterone.

Ovary Structure

• Composed of two layers (medulla and cortex)
• It contains a reserve of follicles

Uterine Tube (Salpinx, Fallopian tube)

• Catches the oocyte post-ovulation, serving as the site of fertilization.
• Delivers fertilized ova to the uterine horn.
• Features an infundibulum, a funnel-shaped part that covers the ovary to capture oocytes after follicle rupture.

Uterus

• Serves as the site of gestation; ensures physiological exchanges between the fetus and the mother.
• Structure includes the endometrium (mucosa), myometrium (muscle), and perimetrium, attaching via broad ligaments.
• "Y" Shaped
• Contains uterine horns (long) and uterine body (short)
• In the pelvic cavity after gestation.

Cervix

• Manages passage to and from the vagina.
• Partially projects into the vaginal lumen.

Vagina and Vestibule

• The copulatory organ & birth canal
• The urethral orifice separates the vagina from the vestibule.
• The vestibule combines reproductive and urinary system functions.

Vulva

• The ventral commissure is pointed
• Fossa clitoridis & clitoris cannot be confused with the urethral orifice
• Dorsal commissure is rounded

Placenta

• A temporary organ for gestation
• Placental structure varies among species.
• In the bitch, the placenta is zonary with three zones: transfer, pigmented (at either end of transfer zone), and a relatively nonvascular zone.

Mammary Glands

• Modified sweat glands that produce lactation.
• The number of pairs varies by species; bitches usually have 5 pairs.
• Lymphatic drainage is important for surgical removal of tumors.