Calcium binding sites in the insect polytrophic egg vesicles as possible markers of the route of inflow of calcium.

Calcium binding sites were revealed in the polytropic egg vesicles of Galleria mellonella (Lepidoptera) by fixation of the ovariole with glutaraldehyde in the presence of excess of calcium. Calcium dependent deposits appeared in the mitochondrial matrix in cells of the epithelial sheath and of the follicular epithelium. The deposits were also seen in the extracellular space around the follicular epithelial cells and around the trophocytes , at the oolemma, and in the coated vesicles of the oocytes at the stage of vitellogenesis. On the other hand, the deposits were not detected in the mitochondria of the trophocytes and the oocytes. Considering the high content of calcium in the insect oocyte ( Przel ecka et al. [17]) the possible route of entry of calcium to the oocyte is discussed on the basis of distribution of the visualized calcium binding sites.