An embryo (from Greek: ἔμβρυον, plural ἔμβρυα, lit. "that which grows," from en- "in" + bryein "to swell, be full") is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination. In humans, it's called an embryo from the moment of fertilisation until the end of the 8th week, whereafter it's instead called a fetus. Deve… (More on Embryos)