In the female sex the first stage of the development of gametes is similar to that found in spermatogenesis – the oogonia—the cells eventually giving rise to the eggs— undergo proliferation by mitotic divisions. They then become oocytes and enter a period of growth. Owing to the fact that the egg contributes the greater part of the substances used in [...]
As the oocyte grows and as various inclusions are produced in its cytoplasm, a pattern of organization gradually emerges, which will be of importance when the eggs start developing. The arrangement of various substances and cellular constituents in the advanced oocyte and, later, in the egg shows a polarity, that is, an unequal distribution with respect to what may be [...]
During the growth of the oocyte not only does the amount of cytoplasm increase in quantity, but it changes in quality by the elaboration and regular distribution of various cell inclusions and specially modified parts of the cytoplasm which, are essential for the development of the embryo. In most animals which have been investigated with modern methods, young oocytes show [...]