Which germ layer forms the lining of the digestive and respiratory systems?

Which germ layer forms the lining of the digestive and respiratory systems?

• A. Endoderm
• B. Ectoderm
• C. Mesoderm
• D. Chorion

Answer: (A)

Endoderm forms the lining of the digestive and respiratory tracts. This germ layer gives rise to the mucosal epithelium of the gut and airways and to associated glands, such as the liver and pancreas. The other layers have different roles: ectoderm becomes the skin and nervous system; mesoderm develops muscles, bone, blood vessels, and connective tissues; and chorion is an extraembryonic membrane involved in supporting the embryo, not a germ layer lining internal organs.

Endoderm forms the lining of the digestive and respiratory tracts. This germ layer gives rise to the mucosal epithelium of the gut and airways and to associated glands, such as the liver and pancreas. The other layers have different roles: ectoderm becomes the skin and nervous system; mesoderm develops muscles, bone, blood vessels, and connective tissues; and chorion is an extraembryonic membrane involved in supporting the embryo, not a germ layer lining internal organs.