LIGHT AND ELECTRON-MICROSCOPIC STUDIES ON THE SEMINAL SECRETIONS AND THE VAS-DEFERENS OF THE PENAEIODEAN SHRIMP, SICYONIA-INGENTIS

Unlike the other penaeiodean shrimp, the ridge back shrimp, Sicyonia i ngentis does not produce a spermatophore, but transfers sperm suspende d in seminal plasm. This paper reports on the histomorphology and ultr astructure of the vas deferens with reference to its functional role i n secreting the sperm hearing materials. The vas deferens is divisible into proximal secretory, mid storage and distal ejaculatory regions. The epithelial cells lining the proximal vas deferens are comprised of secretory and absorptive cell types. The loose sperm cells found in t he lumen of this region are in an immature condition, and are agglutin ated into a compact mass with signs of spermiogenesis in the mid vas d eferens, The epithelial cells lining the mid vas deferens are short fl attened cells. The distal vas deferens is ensheathed by muscular fibre s. The inner epithelial cells are highly secretory and contain numerou s microvilli at the luminal end. The sperm cord gets liquefied in this region facilitating the transfer of sperm in liquid form to the femal e during mating.