Species Variation in Accessory Sex Glands of Male Animals

Species variation in accessory sex glands of male animals is significant and reflects adaptations related to reproductive strategies across different species.

The accessory sex glands present in male animals are the seminal vesicle, prostate, and Cowper’s gland.

1. Seminal Vesicle

Bull

The seminal vesicles of the bull are two compact, glandular organs with a lobulated surface. They are located on the dorsal surface of the bladder and are related dorsally to the rectum. Each gland measures approximately 10 to 12 cm in length, 5 cm in width, and 3 cm in thickness. Structurally, each consists of a thick-walled tube folded upon itself in a tortuous manner. The excretory ducts open on either side of the colliculus seminalis, lateral to the openings of the vas deferens, at the ejaculatory orifices.

Ram and Buck

The seminal vesicles of the ram and buck are similar to those of the bull or ox.

Stallion

The seminal vesicles of the stallion are two elongated, pyriform sacs. Each consists of a rounded blind end (fundus), a narrow middle part (body), and a caudal constricted part (neck or duct). Each gland measures approximately 15 to 20 cm in length.

The excretory duct opens either in common with or alongside the vas deferens within a pouch of mucous membrane located on the side of the colliculus seminalis.

Boar

The seminal vesicles of the boar are exceedingly large, distinctly lobulated, and highly glandular. From the medial surface of each gland, about half a dozen or more large, thin-walled ducts emerge and converge into a smaller excretory duct, which terminates at a slit-like opening on the colliculus seminalis.

Dog

The seminal vesicle is absent in the dog.

Rabbit

The seminal vesicle of the rabbit is medially situated and opens into the prostatic segment of the urethra, just anterior to the colliculus seminalis.

Cock

The seminal vesicle is absent in the cock.

2. Prostate Gland

Bull

The prostate of the bull is a musculo-glandular organ, pale yellow in color. It consists of two parts: the body and the pars disseminata.

The body is a small mass that stretches across the dorsal surface of the neck of the bladder and the origin of the urethra. The pars disseminata surrounds the pelvic part of the urethra.

Prostatic secretions are carried by ducts that open into the urethra behind the colliculus seminalis in rows — two between the folds of mucous membrane passing backward from the colliculus seminalis, and two more on either side, lateral to the folds.

Buck and Ram

The prostate of the buck and ram is entirely disseminate, with no distinct body portion.

Stallion

The prostate of the stallion is a lobulated gland that lies on the neck of the bladder. It is large and consists of two lateral lobes connected by an isthmus.

The superficial surface of the lobes is related to the rectum, while the deep surface is concave and associated with the seminal vesicle.

The isthmus is located ventrally, near the uterus masculinus and the vas deferens. There are 15 to 20 ducts on either side, opening laterally to the ejaculatory orifices.

Dog

The prostate of the dog is very large, globular, and surrounds the neck of the bladder. A median furrow divides it into two lobes. The prostate has numerous ducts.

Boar

The prostate of the boar is concealed by the seminal vesicle. The body of the gland overlies the neck of the bladder.

Rabbit

The prostate of the rabbit lies in the dorsal wall of the more caudal part of the seminal vesicle.

Cock

The prostate is absent in the cock.

3. Cowper’s Gland

Bull

The Cowper’s glands of the bull are small, paired glands located on either side of the pelvic urethra.

Stallion

The Cowper’s glands of the stallion are also small, paired glands situated on either side of the pelvic urethra.

Boar

The Cowper’s glands of the boar are similarly small and paired, located just ventral to the prostate gland.

Dog

The Cowper’s glands in the dog are located at the level of the pelvic urethra, near the prostate gland.

Rabbit

The Cowper’s glands of the rabbit are situated at the junction of the pelvic urethra and the prostate segment.

Cock

The Cowper’s gland is absent in the cock.