HISTOLOGICAL ANALYSIS OF THE MALE GONADS OF THE BRACHYURAN CRAB Perisesarma bidens (DE HAAN, 1835)

This paper provides the morphology of the male reproductive system and spermatophore formation in the brachyuran crab, Perisesrma bidens. The male reproductive system comprises of paired symmetrical testis, highly coiled vas deferens, saccular accessory glands and ejaculatory duct which opens out as intromittent organ. The testicular tubules display three zones: germinal zone (GZ), transformation zone (TZ) and evacuation zone (EZ). Histologically, the testes consist of large number of testicular lobes containing spermatogonial cells that differentiate into spermatocytes and a collecting duct. Spermatogenesis occurs within the testis and subsequently reaches the vas deferens through the collecting duct.  Anatomically and physiologically the vas deferens is divided into anterior vas deferens (AVD), middle vas deferens (MVD) and posterior vas deferens (PVD). The columnar epithelium of AVD secretes glycoproteinaceous and mucoproteinaceous secretions to assist in grouping of sperms and spermatophore formation. MVD and PVD are filled with granular glycoproteins and alcianophilic secretions encapsulating spermatophores. The accessory gland seretions are akin to PVD and the enormous amount of these ductal secretions possibly supports easy transport of spermatophores during copulation. The ejaculatory duct is multilayered structure and extrudes the spermatophore and seminal secretions towards the gonopores. A delicate tissue attached to the ejaculatoryduct  is androgenic gland. This reproductive study would obviously help us to clarify some of the aspects of seminal biology and its function during fertilization, a process which highlights interesting peculiarities in crabs.