The three germ layers are the endoderm, mesoderm, and ectoderm.
Work Step by Step
The endoderm, the innermost germ layer, gives rise to the lining of the digestive tract and respiratory system. The muscles and the organs of the circulatory, reproductive, and excretory systems arise from the mesoderm, the middle germ layer. The outer germ layer, the ectoderm, gives rise to the sense organs, nerves, and outermost skin layer.