The development of the spermatozoa takes place in the male gonads, the testes. In vertebrates and insects, the testes are composite organs consisting of numerous seminiferous tubules, or seminiferous lobules, converging toward common ducts which lead the mature sperm to the exterior. Spermatogenesis is a continuous process, and various stages of development of the sperm may be observed in the [...]
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 [...]
Messenger RNA is the link between the genome and the cell cytoplasm. For this reason alone it is of central importance in the study of gene action. This study has been greatly facilitated by the methods which are now available for the isolation and purification of mRNA's (and other RNA's as well). Purified mRNA is, of course, a prerequisite for [...]