[Ultrastructure and dynamics of the transosomes of the follicular epithelium of avian ovaries].

Specific organelles in follicular cells of the avian ovaries - so called transosomes - are described. Transosomes are formed in the follicular cell cytoplasm under the cytoplasmic membrane and consist of a dense layer 100-150 A in thickness and granules 110-250 A in diameter evenly distributed on its inner surface and containing r-RNA. The main property of transosomes is to move from one follicular cell to another or to an oocyte having separated from numerous processes of follicular cells and being surrounded by two additional membranes. In the ooplasm the transosome takes part in the development of primordial yolk granules. It is supposed that transosomes bring about a transmission of somatic follicular cells to the occyte which is necessary for the initial stages of vitellogenesis.