The male accessory glands are the ampullary gland,
seminal vesicle,
prostate,
bulbourethral gland, and
urethral gland. The products of these glands serve to nourish and activate the
spermatozoa, to clear the urethral tract prior to
ejaculation, serve as the vehicle of transport of the spermatozoa in the female tract, and to plug the female tract after placement of spermatozoa to help ensure
fertilization. Although the glands are usually described as being branched
tubular or branched
tubuloalveolar, they vary in their organization and in their distribution in different species.
Ampullary glands Each of these branched tubular glands lined by simple columnar
epithelium is an enlargement of the
vas deferens in its terminal portion. These are typical tubular glands in
ruminants, horses and dogs; absent in the cat and poorly developed in boars. The function of the white
serous secretion is not known.
Seminal vesicles The secretory endpieces of these glands are lined with simple columnar
epithelium; the main ducts are lined with stratified columnar epithelium. These glands do not occur in
carnivores, but are present in some form in horses,
ruminants and swine. Seminal fluid, the product of this gland, serves as a vehicle for the transport of
spermatozoa.
Prostate gland Grossly the
prostate gland can be divided into two parts: the body and the disseminate part. Low cuboidal to low columnar
epithelium provides the lining for this compound,
tubuloalveolar gland which consists primarily of serous secretory end pieces. The secretion of this gland is more serous in dogs and more mucous in bulls. It serves to promote the movement of
spermatozoa and to form a
vaginal plug. Additionally, in bulls, the secretion contains high amounts of
fructose and
citric acid.
Concretions may be present in the secretory end pieces as well as parts of the duct system. The prostate and Cowper's glands are the only male accessory glands in marsupials.
Bulbourethral glands The lining of these paired, compound,
tubuloalveloar glands is simple columnar
epithelium. A capsule of dense
connective tissue contains some
smooth muscle as well as
skeletal muscle of the
bulbospongiosus and
urethral muscles. All domestic species have these glands except the dog, and their
mucus secretion serves to clear the
urethra of
urine and to lubricate it and the
vagina. The product may also serve as an energy source for the
spermatozoa.
Urethral glands In some species, branched tubular
mucous glands are found along the length of the
urethra, especially dorsal to the
lumen of the urethra. The exact function of their product is not clear. == Distribution in insects ==