Morphogenesis of an Ectodermal Derivative
During the development of vertebrate body the dissimilar regions in the three germ layers of the gastrula become segregated from each other to make the rudiments of future organs and tissues. In this the partitioning of ectoderm as well as the formation and inward displacement of neural tube in frog and chick. The process is termed as neurulation. We have chosen to discuss the neurulation process since the external morphology of developing embryo at this stage is dominated by the developing nervous system and the embryo itself is known as neurula at this stage. We shall begin along with the separation of ectoderm into subpopulations of cells, 'each of which will develop into distinct ectodermal organ. The ectodermal layer essentially separates into
- Epidermal ectoderm from which the skin is formed,
- Neural ectoderm which gives rise to central nervous system and
- Neural crest which gives rise to a portion of peripheral nervous system and a variety of other tissues.