First germ layer to be formed is:: (A) Ectoderm, (B) Endoderm, (C) Mesoderm, (D) All of them develop simultaneously
Answer is B. Ans. B EndodermRef: Netter's Atlas of Embryology, 2012 ed. pg. 47* Epiblast is the source of all three germ layers and endoderm is the first germ layer to be formed.