The zygote appears from the fusion between the egg and sperm. The zygote is formed by only one cell and the cores of the egg and sperm can be observed in its centre.
By Aitziber Domingo Bilbao B.Sc., M.Sc. (embryologist), Andrea Rodrigo B.Sc., M.Sc. (embryologist) and Sandra Fernández B.A., M.A. (fertility counselor).
Last Update: 02/02/2017