In this article we will discuss about the process of gastrulation in amphioxus and amphibians. Gastrulation in Amphioxus: In Amphioxus, there are differences in the various regions of the egg cytoplasm which permitted Conklin (1932) to trace these regions into the later stages of development and thus to reconstruct a fate map, at least in rough outlines. At the beginning [...]
In this article we will discuss about the process of maturation of eggs in the female gamete. After the oocyte completes its growth, it is ready for the reduction divisions. By this time, the chromosomes of the oocyte have reached the stage of diakinesis. The meiotic division in the female gametes cannot, however, proceed in the same way as in [...]
All eggs, like any other cells, are of course covered by the cell membrane or plasmalemma. Under the electron microscope the plasmalemma sometimes can be seen to be double, with two layers of electron-dense material about 50 Å thick separated by a less dense interval of about 60 Å. In addition to the plasmalemma, eggs of all animals, with the [...]