presomite embryo

embryo /em·bryo/ (em´bre-o)

1. in animals, those derivatives of the zygote that eventually become the offspring, during their period of most rapid growth, i.e., from the time the long axis appears until all major structures are represented.

2. in humans, the developing organism from fertilization to the end of the eighth week. Cf. fetus.

3. in plants, the element of the seed that develops into a new individual.em´bryonalembryon´ic

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presomite embryo  the embryo at any stage before the appearance of the first somite.

previllous embryo  the embryo before the placental chorionic villi develop.

somite embryo  the embryo between the appearance of the first and the last somites.

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presomite embryo

[prēsō′mīt]

Etymology: L, prae + Gk, soma, body, en, in, bryein, to grow

an embryo in any stage of development before the appearance of the first pair of somites (segments), which in humans usually occurs around 19 to 21 days after fertilization of the ovum.