Two types of nuage aggregates, the mitochondria-associating nuage and the freely-existing nuage, appeared in the cytoplasm of the growing Chinese hamster oocytes in a growing stage-specific manner. Enzyme digestion studies on the ultrathin sections obtained from the glycol methacrylateembedded materials showed that both types of nuage contain RNA and proteins. The ethanol-phosphotungstic acid staining and also the cobalt thiocyanate staining used to examine the localization of basic proteins at the ultrastructural level revealed that the mitochondria-associating nuage contains a considerable amount of basic proteins, whereas only a few may be present in the freely-existing nuage.
It was considered that the mitochondria-associating nuage may lose its basic proteins and transform into the freely-existing nuage, along with the oocyte's growth.