A) morula is a solid ball of tightly packed cells, whereas the blastula has a cavity in the center.
B) blastula has fewer cells than the morula.
C) morula has a hollow center, but the blastula doesn't.
D) morula is a well-developed embryo, and the blastula is an earlier stage of development.

A) morula cells
B) the animal pole
C) the blastocoel
D) neural crest cells
E) notochord cells

A) embryo.
B) blastula.
C) morula.
D) gastrula.
E) zygote.