Oosome formation in two ichneumonid wasps.

During oogenesis of two hymenopteran species. Cosmoconus meridionator and Lissonota catenator, the place of origin and the ways of transport of two oosome components have been shown. The first constituent is produced in the trophocytes cytoplasm as the nuagemitochondria complexes (NM complexes). The NM complexes subsequently are transported via intercellular bridges to the oocyte and along the oolemma to its posterior pole. At the same time, near the posterior pole, the other structures connected with the oosome formation appear. Most probably they are produced in the ooplasm and have the appearance of nuage of moderate density (NMD). The two structures are composed of proteins and do not contain RNA (toluidine blue test). The NM complexes as well as the NMD disappear as the definite oosome forms at the posterior pole of the oocyte. At the same time the oosome becomes RNA positive. It is suggested that the oocyte nucleus is not involved in the process of the oosome formation.