Gynecology & Obstetrics
Open Access

Embryogenesis

Embryonic development, also embryogenesis, is the process by which the embryo forms and develops. In mammals, the term refers chiefly to early stages of prenatal development, whereas the terms fetus and fetal development describe later stages.

The stages of embryogenesis are described in more detail below.

Stage 1: The process of embryogenesis begins with an egg or ovum being fertilized by a sperm cell to form a zygote. ... Stage 2: Over the next three days, the zygote undergoes a number of cell divisions, a process referred to as cleavage.  Embryogenesis is the development of a fertilized egg that occurs early on in pregnancy. After a sperm fuses with an egg, many changes occur in a specific order. The cells divide, reorganize and form layers of tissue that will eventually develop into specific organs.