Literally, embryology is the study of embryos, where embryo denotes the juvenile stage, either within the eggshell, egg membranes or in the mother's womb. In the development stage, the embryo undergoes a number of changes. The changes occur not only in the body of the larva but also in habit or behaviour also. It is due to these dramatic changes that embryology has now been termed' Development Biology' preferably. Metamorphosis, embryonic in ductwork embryonic nutrition, regenerator cleavage, Parthenon genesis (development of egg without fertilization), gametogenesis and fertilization are few of numerous other points of study under embryology. The present encyclopedic work would cater to the maximum requirements of thebe-enthusiasts.