The function of the spermatozoon, for which its whole organization is adapted, is to reach the egg and, by fusing with the egg, to cause the egg to start developing and to transmit to the developing embryo the paternal genes. In most cases this means that the spermatozoon must have a high degree of mobility, and in fact, the organization [...]
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 [...]