A correct interpretation of gastrulation is impossible without a knowledge of the position which the presumptive germinal layers occupy in the blastula. This position may be ascertained in various ways. A chart, showing the fate of each part of an early embryo, in particular, a blastula, is called a fate map. In tracing the fate of various parts of the [...]
In this article we will discuss about the gene activity during gastrulation period of embryos. Fragments of sea urchin eggs not containing the nucleus may be treated with agents who cause parthenogenetic activation of the egg (viz., hypertonic seawater). It has been found that the non-nucleated fragments begin to cleave and may reach the morula stage. The animals (embryos), however, [...]
In this article we will discuss about the concept of gradients in the development of embryo. The Dorsoventral and Anteroposterior Gradients : The phenomenon of regional specificity raises the question of whether the gray crescent does not contain, after all, two or even more different specific substances, responsible for the development of the head and the trunk regions (or the [...]