The Seminal Vesicle (Vesicular Gland) in Male Animals

The seminal vesicle is a paired accessory sex gland located on the floor of the pelvis, positioned dorsally and laterally to the ampulla or the neck of the urinary bladder.

The seminal vesicle, also known as the vesicular gland, is present in all domestic animals under this name except in the stallion.

In the stallion, the seminal vesicle is more bladder-like in structure, with glandular tissue located on the walls and a large central dilatation. In ruminants and boars, the gland is lobulated, with each lobule containing a small central cavity.

The secretion from the seminal vesicles contributes nutrients, volume, and buffering capacity to the semen, but the gland does not store spermatozoa. The ducts of the seminal vesicles open into the pelvic urethra, in close proximity to the opening of the vas deferens at the colliculus seminalis.

Functions

The salient physiological functions of the seminal vesicles are:

• To produce vital biochemical secretions. The seminal vesicle is the site for the production of fructose and citric acid. Fructose is the main source of nutrition/energy for spermatozoan motility. The remaining biochemicals are also essential for spermatozoal survivability and maintenance.
• To secrete vesicular fluid. The seminal vesicle is the main source for the production of the liquid part of the ejaculate. The vesicular fluid, in its liquid state, is the main source of flow current and gives impetus for floating vesicular motion due to the surface tension of its liquid state, which helps the male gamete during its swimming in the liquid seminal plasma by propelling the spermatozoal locomotory apparatus through dynamic energy.
• The liquid secretion of the seminal vesicle helps in the lubrication of the urethra for the movement of spermatozoa.
• The final volume of semen is related to the quantity of secretion from the seminal vesicle.

Blood Supply

Both the middle rectal artery and the inferior vesical artery supply the seminal vesicle, and they are branches of the internal iliac artery. The vesical venous plexus is responsible for the venous drainage of the seminal vesicle.

Nerve Supply

The muscular wall of the seminal vesicle is supplied with a plexus of nerve fibers and contains small sympathetic ganglia.

Species Wise Anatomy

• Bull: The vesicular glands are lobulated, measuring 10–15 cm in length and 2–4 cm in diameter.
• Stallion: The seminal vesicles are smooth, measuring 15–20 cm in length and about 2.5–5 cm in diameter. A small portion of the seminal vesicle is covered with peritoneum in both the bull and the stallion.
• Boar: The vesicular glands are proportionately very large, measuring 12–15 cm in length, 5–8 cm in width, and 5–8 cm in thickness. They cover the caudal portion of the bladder and extend into the abdominal cavity. The volume of ejaculated semen is highest in the porcine species, likely due to the comparatively larger and heavier size of the seminal vesicles in the boar. This may be a characteristic feature of the species.
• Ram and Buck: The vesicular glands resemble those of the bull.
• Dog and Cat: The seminal vesicle is absent in both the dog and the cat.