Post-embryonic Development of the Seminal Vesicle in the Stingless Bee Melipona quadrifasciata Lepeletier, 1836 (Apidae: Meliponini)

The male accessory glands of stingless bees (Apidae: Meliponini) are absent and the morphology of their seminal vesicle indicate probable secretory function by this organ. This study investigated the post-embryonic development of the seminal vesicles in males of the stingless bee Melipona quadrifasciata by histology and histochemistry. White-eyed pupae, pink-eyed pupae, brown-eyed pupae, black-eyed pupae, newly emerged and sexually mature males were studied. Seminal vesicle has a wall with a single layered epithelium onto a thin basement membrane, followed by a well-developed muscle layer. The epithelium is polarized in the pupal stage with basal cell region strongly positive for glucoconjugates and carbohydrates. The seminal vesicle has an enlarged lumen from the young pupal stages with luminal content increasing gradually with glucoconjugates along the pupal development. In the newly emerged and mature males, the histochemical tests to carbohydrates were negative. In the sexually mature males, spermatozoa clusters are embedded by the glucoconjugates content of the seminal vesicle lumen. In conclusion, the seminal vesicle of M. quadrifasciata has a secretory function during the pupal stage and in newly emerged males, whereas in adult males this organ stores the spermatozoa.