WANI Dictionary

Embryo

An embryo is an animal individual after fertilization and before hatching or birth.

Definitions in the literature

• in animals, the stages of development that begin with the fertilization of the egg cell and the end with hatching or birth; in mammals, the early stages in which the developing animal does not yet resemble the adult of the species [1].
• An animal in the earliest stages of its development, from the time when the fertilized ovum starts to divide (see CLEAVAGE), while it is contained within the egg or reproductive organs of the mother, until hatching or birth [2].