What is the meaning of Blastula?

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

blastula (an early form in the development of an embryo)

blastula (an early form in the development of an embryo)

blastula (an early form in the development of an embryo)

blastula (early form in the development of an embryo, consisting of a spherical layer of cells filled with fluid)

Source: wiktionary.org