In which of the following stages of embryo development are the three primary germ layers first present?

In which of the following stages of embryo development are the three primary germ layers first present?
A . Blastula
B . Zygote
C . Gastrula
D . Coelomate
E . Morula

View Answer

Answer: C

Explanation:

The gastrula is formed from the blastocyst, which contains a bilayered embryonic disc. One layer of this disc’s inner cell mass further subdivides into the epiblast and the hypoblast, resulting in the three primary germ layers (endoderm, mesoderm, ectoderm).