BLASTULA

blastula, blastosphere

(noun) early stage of an embryo produced by cleavage of an ovum; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs

Source: WordNet® 3.1

Etymology

Noun

blastula (plural blastulas or blastulae)

(embryology) An early form in the development of an embryo, consisting of a spherical layer of cells filled with fluid; a blastosphere.

Source: Wiktionary

Blas"tu*la, n. Etym: [NL., dim. of Gr. a sprout.] (Biol.)

Definition: That stage in the development of the ovum in which the outer cells of the morula become more defined and form the blastoderm.

Source: Webster’s Unabridged Dictionary 1913 Edition