mechanism of gastrulation -it is most impotant

Question

MECHANISM OF GASTRULATION -

1. It is most impotant stage of embryonal development, in which single layered blastula converts into 2 or 3 layered gastrula.
2. During this stage, rearrangement or migration of blastomeres pressent on the surface of blastrula takes place i.e. differentiation of blastomeres in ectroderm, mesoderm and endoderm occurs during this stage.
3. The movements of blastomeres during gastrulation are called Morphogenetic movements or formative movements.
4. During the process of gastrulation, each type of blastomere performs a specific movement to meet its proper destiny.
5. Most of the deformities of embryo are due to wrong movement and wrong position of blastomeres.
6. However, the gastrular movements can be broadly divided into 2 kinds -   1. Epiboly  2. Emboly