Accessory genital glands open into the urethra and include seminal vesicles, prostate and bulbourethral or cowper’s glands.
Seminal vesicle
Seminal vesicle of bull is a thick-walled sacculated tube bent on itself several times in a tortuous manner, to form lobules separated by heavy smooth muscular septa. The capsule and the septa contain abundant plain muscle fibres, a feature characteristic of all accessory glands. The mucosa is thin shows primary folds which branch into secondary and tertiary folds.
These project into the lumen and forms by anastomosis numerous cavities of different sizes separated by thin partitions of lamina propria, all open into the large central cavity. Epithelium is pseudostratified columnar being composed of columnar cells and irregularly shaped basal cells.
Seminal Vesicles are absent in carnivores. In horse they are true vesicles showing mucosa, muscularis and adventitia.
Prostate gland
Prostate is a compound tubulo-alveolar gland surrounded by a capsule, which contains abundant plain muscular tissue. From this capsule broad septa penetrate and form a network in the interior of the gland.
The septa and the abundant stroma, which separates the alveoli, contain plenty of plain muscle fibres. The alveoli are lined by columnar epithelium. They show folds, which subdivide the lumen into compartment. The columnar cells may be tall or short, cytoplasm of cells is finally granular. Each lobule is traversed by an axial duct. Ducts are lined by columnar epithelium, but near termination in the urethra it becomes transitional.
Cowper’s gland
Each is a lobulated compound tubuloacinar gland covered by a fibrous capsule overlaid by striated muscle. The stroma between the alveoli consists of fibro-elastic tissue with a few plain muscle fibres.
The secretory portions may be tubular or alveolar. Lining epithelium shows variations depending on functional stage. It may be columnar or cuboidal. Most of the columnar cells are of the mucous type, but the nucleus is spherical, located at the base of cells.
The cytoplasm stains basophilic but some cells may show a granular acidiphilic cytoplasm. Smaller ducts are lined by simple columnar epithelium and main ducts stratified columnar epithelium. Cowper’s glands are absent in carnivores.
