Germ cell determinants in the oocytes of freshwater sponges

Abstract

The paper reports a light and electron microscopy study of the ultrastructure and oogenesis of germ-cell determinants in freshwater sponges Eunapius fragilis and Swartschewskia papyracea. For the first time, germinal granules surrounded by mitochondria, the ultrastructural signature of germinal plasma in a number of metazoan organisms, has been described in Porifera. Structural changes in germ determinants in the course of oogenesis have been described, and participation of mitochondria in the formation of the central component of germ cell determinants has been suggested.