Spermatogenesis in the carnivorous sponge Lycopodina hypogea (Porifera, Demospongiae)

Carnivorous sponges (family Cladorhizidae) lack the aquiferous system and choanocytes and, therefore, their reproduction in particular spermatogenesis is unusual for Porifera. We studied a carnivorous sponge Lycopodina hypogea using confocal microscopy, SEM TEM. In brief, L. proceeds as follows. Male cells derive from archaeocyte-like cells. During its first divisions, spermatogonia are surrounded by thin follicle made up single cell. The divide mitotically, giving rise to next generation of spermatogonia, primary spermatocytes secondary spermatocytes. Spermatozoa long narrow mono-flagellated cells, tightly packed inside spermatic cyst. They sponges, being dart-shaped, with an anterior filament, which electron-dense, rod-like outgrowth terminating acrosome. flagellum long, proximal region located within cytoplasmic tunnel. course spermiogenesis, envelope several intertwined pseudopodia formed around unicellular envelope. Symbiotic bacteria usually present between sperm maturation, cyst, may be called spermatophore, migrates body filaments acquires two bundles forceps spicules. Mature spermatophores released filaments. To sum up, we showed that fertilization strikingly different these processes other sponges. differences mostly concern origin male germ structure mature spermatozoa formation spermatophores.