Which Embryonic Germ Layer Forms the Linings of the Respiratory

Question

Which embryonic germ layer forms the linings of the respiratory and digestive tracts?
A) mesoderm
B) ectoderm
C) trophoderm
D) endoderm
E) epiderm

Accepted Answer

The endoderm is the embryonic germ layer that forms the linings of the respiratory and digestive tracts. The mesoderm gives rise to muscle, bone, cartilage, and blood vessels, while the ectoderm gives rise to skin, hair, nails, and the nervous system. Trophoderm is not a germ layer, but rather a layer of cells that forms the outermost layer of the blastocyst in placental mammals. Epiderm is also not a germ layer, but rather a term used to describe the outermost layer of cells in the skin.