VAna Urogenital

• Urinary System Functions


  • Regulate the chemical composition and volume of the body fluids (osmoregulation)
  • Remove nitrogenous waste products and excess water from the body (excretion)
  • Act as endocrine gland by the secretion of the hormone erythropoietin
• Kidneys

  • Perirenal fat - mass of protective fat surrounding the kidney and holding its place
  • Fibrous capsule - loosely attached (except at the hilus) covering the kidneys
  • Renal cortex - outer layer of the kidney parenchyma beneath the capsule; characterized by their light color and granular appearance
  • Renal medulla - inner layer of the kidney parenchyma; characterized by the striated appearance
  • Renal crest - ridge resulting from the complete fusion of the medulla and pyramids
  • Renal calyx - cup-shaped structure receives urine from the renal papillae
  • Renal sinus - space occupied by the ureter, renal blood vessels and nerve entering the kidney
  • Renal hilus - opening to the renal sinus
  • Renal pelvis - expanded proximal end of the ureter
• Ureter


  • Muscular tube
  • Divided into abdominal or pelvic part
  • Turns medially to enter the broad uterine ligament in the female and the mesoductus deferens in the male
  • Ends by inserting into the dorsolateral surface of the urinary bladder
  • Length of intramural course prevent reflux of urine into ureter when pressure is raised within bladder but does not hinder further filling of bladder as resistance is normally overcome by peristaltic sonstraction of ureteric wall
  • Peristaltic contractions of the ureteric wall prevents reflux of urine
• Urinary Bladder


  • Hollow musculomembranous organ
  • Collect and stores urine
  • Varies in form, size, and position depending on amount of urine it contains
  • Usually small, globular organ in pubic bone, extends to abdomen (carnivores) but for large animals, more confined in pelvic cavity
  • Body - main part of the bladder having a dorsal and ventral surface
  • Neck - constricted portion of the bladder continuous posteriorly with the urethra (internal; smooth and involuntary control and external sphincter; ring of striated muscle under voluntary control)
  • Fundus - the blunt, flask-shaped anterior extremity
  • Detrusor muscle - smooth muscle of the urinary bladder
  • Ureter ostium - opening for the ureters
  • Trigone - triangular area in the vicinity of the neck
  • Inner layer = Transitional epithelium (enables walls to expand when filling urine)
  • Submucosal layer = Elastic tissue and Smooth muscle (arranged in folds to allow expansion)
  • Peritoneum (surrounds bladder, covers only cranial end lying on abdomen)
  • Bladder is kept in position of three peritoneal folds; Middle umbilical (median/ ventral ligament), Two lateral umbilical folds = contain in their free border the round ligament
• Urethra


  • Tube that conveys urine caudally from the bladder through the pelvic cavity to the outside (female carries only urine, males carry urine, semen, and seminal secretions)
  • Female - urethra is a short tube, opening into the floor of the reproductive tract at the junction of the vagina and vestibule
  • Opening: external urethral orifice
  • Located: urethral tubercle
  • Male - urethra is divided into two parts: Pelvic urethra, Penile urethra
• The reproductive system is important for the perpetuation of life
• The reproductive system has gonads that produce sex-specific gametes
• The reproductive system is provided with tracts enabling the maturation of such gametes
• The reproductive system has structures that enable the meeting of these gametes for fertilizations
• Male Reproductive System


  • Has testes producing spermatozoa at mature age
  • Has accessory sex glands that nourishes the developing spermatozoa
  • Parts include; Testes, Epididymis, Ductus deferens, Urethra, Penis, Accessory sex glands
• Testes


  • Produce spermatozoa
  • Produce fluid to transport and protect the sperm
  • Secrete hormone testosterone
  • Cryptorchidism (failure of testes to descend)
• Scrotum


  • Pouch where testes are located
  • Left testes usually hangs lower than the right
  • Skin (hairless)
  • Tunica dartos (cold) contracts and thickens the scrotal skin, raising the temperature. (Warm) muscle relaxes and turns thinner = cooler
  • Spermatic fascia
  • Cremasteric muscle
• Connective tissue component of testis


  • Tunica albuginea - (white tunic) strong, white fibrous capsule enveloping the testes
  • Mediastinum testis - cord of fibrous tissue running through the middle of the testicle, containing the rete testis
  • Lobules - units of testicles which contain few seminiferous tubules. Separated by septa
• Parenchyma of the Testis

  • Seminiferous tubules - hollow structures in which male germ cells differentiate to spermatozoa. Major parts: convoluted (sperm production occurs) and straight seminiferous tubules (does not produce sperm)
  • Rete testis – network of irregular, interconnecting channels
  • Efferent duct – 8 to 15 channels leading into the head of the epididymis
  • Epididymis – structure adjacent to the testes. Head, Body, Tail
• Ligaments associated with the testis and epididymis

  • Proper ligament of the testis – connects the tail of the epididymis to the ventral extremity of the testis
  • Ligament of the tail of the epididymis and scrotal ligament – connects the tail of the epididymis to the tunica vaginalis parietalis
• Spermatic Cord


  • Vaginal tunic – double wall of serous membrane (visceral and parietal around the spermatic cord and testicle in the male
  • Parietal vaginal tunic – continuation of the abdominal parietal peritoneum through the inguinal canal
  • Mesorchium – serosal fold connecting the visceral tunic with the parietal vaginal tunic
  • Mesoductus - fold of connecting vaginal tunic between the mesorchium and ductus deferens
  • Mesofuniculus – part of the mesorchium between the parietal vaginal tunic and where the mesoductus arises
  • Vaginal cavity – the potential space between the two vaginal tunic layers. It is continuous with a peritoneal cavity at the vaginal ring
  • Vaginal ring – the crescent-shaped opening located on the abdominal side of the deep inguinal ring
  • Pampiniform plexus - coils of testicular veins and artery, making the bulk of the spermatic cord
• Accessory Sex Glands


  • Increase volume of the ejaculate
  • Provide the correct environment for the sperm survival
  • Neutralize the acidity of the urine within the urethra
  • Prostate gland – only accessory sex gland present in the male dog (except for the ampullary gland)
  • Ampullary gland – paired; found in the ampulla
  • Vesicular gland – absent in dogs (paired and secretes fructus, energy source of sperm)
  • Bulbourethral gland/ cowper's gland – absent in dogs
• Penis


  • Copulatory organ of the male
  • Extends from ischiatic arch between thighs
  • Originates as two crura that converge to form the root of the penis, which continues as the body of the penis. penis of the dog is of musculocavernous type
  • Corpura cavernosa – paired, blood filled; made up the dorsal column of the penis
  • Corpus spongiosum - unpaired spongy body; provides the ventral column; more delicate with larger blood spaces
  • Prepuce – cutaneous sheath around the free part of the penis in the nonerect state. Preputial orifice is the opening of the prepuce to the outside
  • Os penis (baculum) - is found on the penises of carnivores. In dogs, its ventral surface is grooved for the urethra
  • Bulbus glandis - part of the glans penis surrounding the proximal os penis. Together with the bitch's vestibular bulb, it is responsible for the "tie" or coital lock in dogs
• Changes in Shape of gland penis during Erection and Copulation

  1. Resting state

  2. Erection - blood fills the cavernous spaces of the bulbus glandis
• Arch


  Between thighs
• Originates as two crura that converge to form the root of the penis, which continues as the body of the penis


  Penis of the dog is of musculocavernous type
• Parts of the penis

  • Corpura cavernosa
  • Corpus spongiosum
  • Prepuce
  • Os penis (baculum)
  • Bulbus glandis
• Corpura cavernosa


  • Paired, blood filled; made up the dorsal column of the penis
• Corpus spongiosum


  • Unpaired spongy body; provides the ventral column; more delicate with larger blood spaces
• Prepuce


  • Cutaneous sheath around the free part of the penis in the nonerect state
• Os penis (baculum)


  • Found on the penises of carnivores, in dogs its ventral surface is grooved for the urethra
• Bulbus glandis


  • Part of the glans penis surrounding the proximal os penis, together with the bitch's vestibular bulb, it is responsible for the "tie" or coital lock in dogs
• Changes in Shape of gland penis during Erection and Copulation

  1. Resting state

  2. Erection - blood fills the cavernous spaces of the bulbus glandis and pars longal glandis

  3. Intermission and engorgement during copulation - contraction of ischiourethral muscle in male and constrictor vestibula in female = venous occlusion of veins, draining penis

  4. When penis is in foenecks of vagina, ligament of the cartilage of os deforms on distal end of glans to form corona glandis

  5. When this shage is attained, opening or urethra faces dorsally in close proximity to cervix of female dog
• Muscles of the Penis

  • Retractor penis muscle
  • Ischiocavernosus muscle
  • Bulbospongiosus muscle
• Parts of the Female Reproductive System

  • Ovary
  • Uterine tube, oviduct or Fallopian tube
  • Uterus – uterine horns and body
  • Cervix
  • Vagina
  • Vestibule
  • Vulva
• The tract is designed to carry several fetuses during a single pregnancy, and it is said to be bicornuate (two horns)
• The bitch bear litters of young thus they are multiparous
• Ovaries


  • Produce ova or eggs ready for fertilization, secrete the hormones estrogen and progesterone, suspended from the body wall by the mesovarium, generally found in the sublumbar region, ranges from 1-1.5 cm, medulla (vascular zone) and cortex (parenchymatous zone)
• Ligaments associated with the ovaries

  • Broad ligament
  • Suspensory ligament of the ovary
  • Proper ligament of the ovary
• Uterine Tubes


  • Paired, convoluted tubes that conduct the ova from each ovary to the respective horn of the uterus, usual site of fertilization of ova by the spermatozoa, infundibulum, fimbria, abdominal ostium of the uterine tube, ampulla, isthmus
• Uterus


  • Cervix (neck) - narrow lumen that's closed most of the time except during estrous and parturition, internal uterine orifice, external uterine orifice, body of the uterus, horns of the uterus
• Vagina


  • Leads from the cervix to the external urethral orifice, lining epithelium is folded longitudinally to allow width waist (?) expansion during parturition and is surrounded by layers of smooth muscles
• Vestibule


  • Leads from the external urethral orifice to the vulva and is shared by both the urinary and reproductive tracts
• Vulva


  • Terminal and the only external part of the female genital tract, has a rounded dorsal commissure and has a more ventral commissure, labia, clitoris, vaginal recess, vestibular bulbs, vestibular gland
• Mammary Glands


  • Cranial thoracic
  • Caudal thoracic
  • Cranial abdominal
  • Caudal abdominal
  • Inguinal mammary gland