An early form in the development of an embryo, consisting of a spherical layer of cells filled with fluid; a blastosphere.
In the reproductive cycle, the stage after the fertilization of the egg that precedes the development into a fetus.
A rudimentary plant contained in the seed.
In viviparous animals, the young animal's earliest stages in the mother's body
The beginning; the first stage of anything.
In humans, usually the cell growth up to the end of the seventh week in the mother's body
An organism in the earlier stages of development before it emerges from the egg, or before metamorphosis.