Embryo

Organisms in the early stages of growth and development.  In animals, embryos are characterized by the cleavage of the fertilized eggs to many cells, the laying down of the three germ layers, and formative steps in organ development.  Although there is some discussion about the characteristics marking the switch from embryo to fetus, in human beings, “embryo” generally refers to the time from implantation to about eight to twelve weeks after conception.

Related Topics:

Genetics

Contributed by: AAAS/DoSER