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 gastrulation and the formation of primary organ rudiments in fishes. In fishes the yolk formed in the oocytes during oogenesis initially does not differ substantially from the yolk in amphibian oocytes and eggs. It consists of yolk platelets lying in the cytoplasm and intermingled with other cytoplasmic components (mitochondria and the like). [...]
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 [...]