Figure 3. Several ultrastructural aspects of a healthy Ircinia fasciculata.

A) Archeocyte of a subectosomal zone, surrounded by numerous cyanobacteria (c) and some heterotrophic bacteria (h); B) Detail of a healthy cyanobacteria, close to an archeocyte plenty of glycogen rosettes (g); C) “symbiotic” bacterial community, typically found in the sponge; D) collagen layer (co) between endopinacocytes (pi) separating two choanocyte chambers (ch: choanocytes); E) collagen bundles, surrounded by endopinacocytes (pi); F) basal section of a choanocyte, full of heterogeneous phagosomes (ph), which is characteristic of the species (n: nucleus).