Definitions

1. noun

A stage in the early development of an animal, especially a vertebrate, characterized by a fluid-filled cavity surrounded by a layer of cells.

“During embryonic development, the blastula is a crucial stage in the formation of the embryo.”

2. plural noun

Blastulae, the early stage of embryonic development in animals, characterized by a fluid-filled cavity surrounded by a layer of cells.

“The blastulae of the frog embryo undergo a series of transformations before hatching.”