This book has been written to cater to the needs of the undergraduate students of Zoology and Medical Science. In the last few decades embryologists have tried their best to solve the problems pertaining to the initiation of life by understanding its various aspects. It is now realised that to solve the puzzle of development genetics cytology, biochemistry and embryology must be studied altogether. Development Biology is a branch of biology which has a tremendous significance in studying the problems of life and its ontogenic development. This ontogenic development gives us a clear understanding of the production of new organisms. In this book every effort has been made to integrate and contribution of experimental embryology and descriptive embryology in the understanding of ontogenic development of organisms. The text has also dealt with postembryology development, regeneration and metamorphosis. The entire ontogenic development is initiated and controlled by genes which have chemical blueprint in their morph that gives instructions throughout are process of development to create a new organism. The schematic illustrations have imparted immense value to this text, and they have all been reproduced meticulously.