Male Reproductive Organs

Epididymis

• The epididymis is a 1 long coiled duct responsible for the maturation and storage of spermatozoa.
• It is composed of 3 parts: head, body, and tail.
• The head is the most proximal portion, receiving sperm from the testes.
• The tail is the most distal portion, continuous with the ductus deferens.

Ductus Deferens

• The ductus deferens enters the abdominal cavity as part of the spermatic chord.
• It crosses the lateral aspect of the urinary bladder to enter the pelvic urethra.
• The ductus deferens is visible on the right testicle or medial view.

Male Urethra

• The pelvic urethra is located within the pelvic cavity and receives the opening of the ducti deferentes.
• The penile urethra exits the caudal aspect of the pelvis and is part of the penis structure.
• The end of the urethra is the external urethral orifice.

Accessory Sex Glands

• There are 4 accessory sex glands responsible for the production of seminal plasma.
• The prostate gland is the only visible accessory sex gland in dogs, surrounding the pelvic urethra.

Scrotum

• The location and orientation of the testes vary per species.
• The scrotum's function is to support the testis and regulate temperature through the dartos muscle.
• The scrotum has a dual chambered pouch, separated by a septum, containing a testis, epididymis, and distal portion of the spermatic chord.

Scrotum Layers

• Outer layer: skin and dartos muscle.
• Middle layer: external and internal spermatic fascia.
• Inner layer: parietal and visceral tunic cavities, and vaginal cavity.

Testes

• The testes migrate from their developmental location near the kidneys to the scrotum.
• They have an ovoid shape and are covered by a tough fibrous capsule, the tunica albuginea.
• The testes have functions of spermatogenesis and endocrine function with testosterone secretion.

Penis

• The penis is the male copulatory organ, composed of 3 parts: root, body, and glans.
• The root is anchored to the ischial arch and is the most proximal part of the penis.
• The glans consists of the bulbous glandis, pars longa glandis, and os penis.

Penis: Erectile Tissues

• The penis erectile tissue includes the corpus cavernosum and corpus spongiosum.
• The corpus cavernosum is the main erectile tissue and will ossify to become the os penis.
• The corpus spongiosum surrounds the penile urethra and expands as the bulb of the penis.

Penis: Erection

• Erection occurs when the retractor penis muscle relaxes, and the erectile tissue fills with blood.
• There are 2 types of erection options: musculocavernous and fibroelastic.
• Musculocavernous is common in dogs, humans, and stallions, and involves a large amount of erectile tissue.
• Fibroelastic is common in bulls, boars, and rams, and involves a limited amount of erectile tissue.

Learn about the anatomy and variations of scrotum in different animal species such as dogs, boars, bulls, rams, and cats. Understand the role of the scrotum in supporting the testes and its structure with a dual-chambered pouch separated by a septum.