Electron microscopical observations on vitellocytes and germocytes inNematoplana coelogynoporoides (Plathelminthes,Proseriata)

Summary Fine-structural features of vitellaria and germaria inNematoplana coelogynoporoides are documented and compared with those of other free-living plathelminths with ectolecithal eggs. Emphasis is mainly put on the pattern of eggshell material, yolk bodies deposited in vitellocytes, and marginal granules of the female germ cells. In this species, encompassed in the taxon Proseriata Unguiphora, the eggshell granules show a meandering pattern also known from species of the taxon Proseriata Lithophora. In contrast, the yolk globules exhibit crystalline components unknown from the Lithophora. The marginal granules in the ooplasm have an extremely large diameter. They consist of a flocculent core and a crescent-shaped cortex. Marginal granules of this appearance have not been found in any other taxon of free-living Neoophora.Abbreviations cc crystalline component - co cortex - gER granular endoplasmic reticulum - go Golgi complex - gl glycogen - lp lipid droplet - mg marginal granule - n nucleus - nl nucleolus - sg eggshell granule - sp spermatozoa - yg yolk globule