Accessory Sex Glands
The male accessory sex glands produce the bulk of the ejaculate, or semen, the medium for transport of sperm. semen provides favorable conditions for nutrition of sperm and acts as a buffer against the natural acidity of the female genital tract.
The accessory sex glands include the ampulla of the ductus deferens, vesicular gland, prostate gland, and bulbourethral gland. Except for the prostate, these glands are paired. There is considerable variation in shape and size of the various accessory sex glands among species, but the relative location is similar in all animals (Figs. 24-1 and 24-8).Ampullae
The ampullae are glandular enlargements associated with the terminal parts of the ductus deferentia. They are well developed in the stal-
Figure 24-8. Accessory sex glands of the bull.
lion, bull, and ram and absent in the boar. Glands of the ampullae empty into the ductus deferentia and contribute volume to the semen.
Vesicular Glands
The vesicular glands (formerly called seminal vesicles) are paired glands associated with the genital fold. in most domestic species, each vesicular gland merges with the ipsilateral ductus deferens, creating the short ejaculatory duct, which empties into the pelvic urethra. In the boar, the vesicular glands open into the urethra separately from the ductus deferentia. The vesicular glands of the stallion are hollow, pear-shaped sacs; those of the bull, ram, and boar are lobulated glands of considerable size.
Prostate Gland
The prostate gland is an unpaired gland that more or less surrounds the pelvic urethra. In farm animals the prostate gland comprises various combinations of diffuse and compact parts extending along the pelvic urethra under cover of the urethral muscle. The multiple ducts of the prostate gland open in two parallel rows, one on each side of the lumen of the urethra. The prostate produces an alkaline secretion that gives semen its characteristic odor. In older intact male animals, the prostate may become enlarged and interfere with urination.
Bulbourethral Glands
The bulbourethral (formerly Cowper’s) glands are paired glands on either side of the pelvic urethra just cranial to the ischial arch but caudal to the other accessory glands. Bulbourethral glands are especially large in the boar.