Sexual reproductive cycles of a Florida, U.S.A., population of four Caribbean carnrnercial
sponge species, Hippospongra laclane, Spoagia barhnra, S. cheiris and S. qraminea, were
determined by analysis of tissue sarnpIes collected over a three-year period. Spermatogenesis in these species was studied using light and transmission electron microscopy. The production of male gametes occurs in cysts within the endosomal tissue of mature specimens. Reproductive elements within an individual cyst develop synchronously while development between cysts is asynchronous. All available evidence suggests that these species are dioecious. Spermatogonia differentiate directly from choanocytes in siru. All cells of the chamber lose their collars and flagella and undergo mitosis to produce primary spermatocytes, each possessing a single flagellurn. The ratio of nucleus to cell diameter In these cells is almost double that of choanocytes. Circumstantial evidence suggests that primary spermatocytes undergo meiosis to produce four spermatids, but confirmational chromatid linkage figures are still lacking. The mature spermatozoa lack both intemediate segments and acrosornes. Male gametes displayed a bright yellow-white autofluorescence when excited with blue light (46s485 nm).