<Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> An embryo is an early stage of development of a multicellular diploid eukaryotic organism . In general, in organisms that reproduce sexually, an embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell . The zygote possesses half the DNA from each of its two parents . In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism . The result of this process is an embryo . </P> <P> In humans, a pregnancy is generally considered to be in the embryonic stage of development between the fifth and the eleventh weeks after fertilization, and is expressed as a fetus from the twelfth week . </P> <P> First attested in English in the mid-14c., the word embryon derives from Medieval Latin embryo, itself from Greek ἔμβρυον (embruon), lit . "young one", which is the neuter of ἔμβρυος (embruos), lit . "growing in", from ἐν (en), "in" and βρύω (bruō), "swell, be full"; the proper Latinized form of the Greek term would be embryum . </P>

When is the fertilized ovum considered an embryo