BRANCHES OF EMBRYOLOGY-
1. DESCRIPTIVE EMBRYOLOGY
This field of embryology is associated with the morphological description of different embryonic stages in the ontoge- netic development of individuals of different species. This involves the initial work of embryologists till 18th century.
2. COMPARATIVE EMBRYOLOGY
It embraces the comparative study of embryology of different animal groups.
3. EXPERIMENTAL EMBRYOLOGY
It involves all those studies that attempt to understand the various fundamental mechanism in the development of different animals, like fertilisation, Cleavage, Gastrulation, Embryonic induction, determination and differentiation.
4. CHEMICAL EMBRYOLOGY
This branch of embryology includes all those studies which employ various biochemical, biophysical and physi- ological techniques for understanding embryological events at molecular level.
It is the branch of embryology concerned with the study of malformations or birth defects. The substances that cause birth defects are called tetratogens. Phocomalia (poorly developed arms child), Ectomalia (arm less child)