Untitled Quiz

Small and Large Animal Male Reproductive Organs

• The presentation covers male reproductive organs in small and large animals.

Male Genital Organs

• Internal pudendal vein and artery are present.
• Lateral caudal artery and vein, artery of penis, caudal rectal artery and vein, urethral artery and vein, ventral perineal artery and vein are all part of the male genital organs.
• Structures like the paranal sinus, right crus of penis (cut), pelvic urethra, deep artery of penis, right dorsal artery and vein of penis, body of penis, superficial branch of dorsal artery, caudal gluteal artery, femoral artery and vein, internal abdominal oblique muscle, cremaster muscle, external pudendal artery and vein, and superficial inguinal lymph node are important parts of the male genital system.

Scrotum

• Protects and supports the testes.
• A dual chambered pouch separated by a septum into right and left halves.
• Each half contains a testis, epididymis, and distal portion of spermatic cord.

Layers of the Scrotum

• Outer skin layer is closely associated with a smooth muscle layer (tunica dartos).
• Spermatic fascia (external and internal) is not distinguished.
• Vaginal tunics (parietal and visceral) are present.
• Vaginal cavity is found between the parietal and visceral layers.

Cremaster Muscle

• Caudal slip of the internal abdominal oblique muscle.
• Attaches to the vaginal tunic near the testis.
• Pulls the testis closer to the body (elevates testes).

Blood Supply: Scrotum

• External pudendal artery is part of the scrotum's blood supply.

Testes

• Male gonads located in the scrotum.
• Surface is invested by the tunica albuginea.
• Covered by the visceral vaginal tunic.
• Orientation depends on species.

Blood Supply: Testes

• Testicular artery forms the pampiniform plexus which convolute around the artery, lymphatics, and nerves.
• Testicular vein also forms the pampiniform plexus.

Descent of the Testes

• Testes migrate from their developmental position near the kidneys to a location outside the body (scrotum).
• There are two phases: extra-abdominal (gubernaculum increases in length and volume) and inguinal canal (allowing testes to pass through).
• The second phase is characterized by regression of the gubernaculum into a small fibrous structure.

Cryptorchidism

• "Hidden testicle"
• When one or both testes are retained or trapped within the abdominal cavity or inguinal canal.

Open vs. Closed Castration

• Closed castration: Incise skin, tunica dartos, and spermatic fascia from parietal vaginal tunic. (Parietal vaginal tunic remains intact)
• Open castration: Incise skin, tunica dartos, spermatic fascia, and parietal vaginal tunic. (Opens vaginal cavity which is continuous with peritoneal cavity)

Spermatic Cord

• Comprised of ductus deferens, testicular artery, vein, and nerves, and their mesorchium membranes (mesoductus deferens).

Epididymis

• Responsible for maturation and storage of spermatozoa.
• Has three main parts: head, body, and tail.
• Sperm enter the epididymis from the testes.
• Tail continuous with the ductus deferens.

Penis

• Two types: Musculocavernosus and Fibroelastic.
• Erection is achieved via relaxation of the retractor penis muscle and blood filling the erectile tissue.

Erectile Tissue

• Musculocavernosus is found in stallion, dog, and tom cat, and has large amounts of erectile tissue.
• Fibroelastic penises have limited erectile tissue, and usually have a sigmoid flexure. (Bull, boar, and ram).

Accessory Sex Glands

• Responsible for production of seminal plasma, and its size decreases with castration.
• The structures include ampulla, vesicular glands, prostate, and bulbourethral glands.

Ampulla

• Enlargement of ductus deferens that opens into the pelvic urethra.
• Present in the stallion, bull, ram. Dog has a similar structure, but not called ampulla.

Vesicular Glands

• Paired glands located dorsocranial to the pelvic urethra, opening into the pelvic urethra.
• Present in stallion, bull, ram, boar.

Prostate Gland

• Located close to the urethra's junction with the bladder.
• Great variation in shape and location across species.
• Corpus and disseminate prostates are present.

Bulbourethral Glands

• Paired, located near the urethra's ischial arch.
• Large in boar.
• Small and buried under the bulbospongiosus muscle in stallion, bull, ram, and tom cat.

Species Table

• Summarizes presence/absence of ampulla, vesicular glands, prostate, and bulbourethral glands in different species (from the table).

Urethra

• Divided into pelvic and penile parts.
• Colliculus seminalis is present.
• Pelvic urethra connects with the pelvic portion, beginning at the ischial arch.
• Corpus spongiosum surrounds the urethra.
• Urethralis muscle is a striated muscle that surrounds the pelvic urethra.

Prepuce

• Fold of skin covering the glans penis.
• Contains an inner and outer lamina
• The lamina forms the fornix, and the urethral opening within the preputial ring.
• During erection, the preputial ring is applied to the penis.

Blood Supply: Prepuce

• Internal pudendal (ventral perineal)
• External pudendal arteries are blood supply to the prepuce.

Blood Supply: Penis

• Internal pudendal is the primary source.
• Ventral perineal, artery of penis, artery of bulb, deep artery of penis, and dorsal artery are all parts of the penis's blood supply.
• Species variations in blood supply (stallion, bull/boar/ram have different arteries).

Blood Supply: Stallion

• (Multiple different arteries involved based on the slides)

Cryptorchidism Description

• More than just one or two retained testes.

CEM in the Stallion

• Swab areas include Distal urethra, (urethral process), Fossa glandis, Urethral sinus, Shaft of penis, and prepuce.

Preputial Diverticulum

• Seen in boars.
• Foul-smelling pheromone containing fluid.

Equine Penis - Glans

• Corona glandis has the greatest circumference.
• Column glandis is a narrowing of the glans.
• Urethral process, fossa glandis, and urethral sinus are also present.

Tom Cat Information

• Cornified spines on the glans penis are testosterone-responsive, present for ~30 days post orhiectomy.

Mechanism of Erection

• Erection is achieved by filling of erectile tissues with blood.
• Parasympathetic (point), and sympathetic (shoot) events.
• Hypogastric and pudendal nerves are involved.

Mechanism of Erection (cont.)

• Blood flow causes the filling of cavernous spaces.
• Veins constrict, preventing venous return.
• Tunica albuginea maintains pressure in erectile tissues.

Upon Intromission

• Contraction of penile musculature pushes blood into the glans penis, causing engorgement of the female vestibular bulbs which further restricts venous outflow.
• This allows engorgement of the penile bulbus glandis.
• The tie is maintained until penile musculature relaxes, and arterial blood pressure returns to normal.