Definitions Found:
An animal embryo at the early stage of development when it is a hollow ball of cells
- blastulaAn animal embryo at the early stage of development when it is a hollow ball of cells
- blastulasAn animal embryo at the early stage of development when it is a hollow ball of cells
- gastrulaeAn embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells