[Oogenesis in Hydra. III. The growth and fusion of the oocytes]

The ultrastructure of oocytes in Hydra has been studied prior to the beginning of their phagocytic activity. The formation of Golgi complexes and vacuolar system by means of the rough endoplasmic reticulum budding and the formation of numerous enzymatic granules within the Golgi complex are considered with respect to the preparation of cells for the processes of phagocytosis and intracellular digestion of structures. The oocyte situated in the center of each accumulation of syncytially connected cells, descendants of one interstitial cell, becomes the egg, whereas all others are consumed by it and transform into endocytes. The partial and complete confluence of oocytes is described. In the first case, a part of cytoplasm of the cells surrounding the growing oocyte is torn away and included in this oocyte. In the second case, the confluence of large oocytes containing endocytes in their cytoplasm takes place. The growing oocyte forms pseudopodia and cytoplasmic processes which move apart the epithelial-muscle cells, reach the mesogloea and come in contact with the gastroderm cells. The role of these contacts in the oocyte growth is discussed.