Histological and Histochemical Studies on the Seminal Vesicles of Donkey (Equus asinus): with Special Reference to their Seasonal Variations

The objective of this study was to describe the histological and histochemical structure of the seminal vesicles during different seasons of the year. The specimens were collected from the seminal vesicles of 24 sexually mature apparently healthy male donkeys (5 to 7 years of age) during different seasons of the year. The seminal vesicles (Vesiculae seminales) of the donkey were paired pear-shaped sacs. The wall of the seminal vesicles of the donkey was consisted of tunica mucosa, tunica muscularis and tunica serosa or adventitia. The tunica mucosa of the seminal vesicle was highly folded, surrounding a large irregular oval central lumen. These folds carried many lateral secondary branches with numerous tubular invaginations into the underlying connective tissue. The lamina epithelialis of the seminal vesicles consisted of principal and basal cells. The activity of seminal vesicles of donkey varied during different seasons of the year. It reached maximal activity during spring which was manifested by increasing in the epithelial height of the glandular epithelium, decreasing the nuclear/ cell ratio and the interstitial/ glandular tissue ratio and increasing the secretory activity. This activity of the seminal vesicles decreased gradually during summer and autumn to reach its minimal during winter. In conclusion, the seminal vesicles of donkey have more pronounced activity in spring than in other season of the year.