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

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

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

Answer: (D)

Endoderm forms the lining of the digestive and respiratory systems. During development, this inner germ layer becomes the mucosal epithelium lining the gut and airways, as well as the glandular tissues associated with them (like the liver and pancreas). The other germ layers have different destinies: ectoderm gives the skin and nervous system, while mesoderm forms muscle, bone, and the circulatory system. The coelom, meanwhile, is a body cavity that arises within mesoderm, not a germ layer itself.

Endoderm forms the lining of the digestive and respiratory systems. During development, this inner germ layer becomes the mucosal epithelium lining the gut and airways, as well as the glandular tissues associated with them (like the liver and pancreas). The other germ layers have different destinies: ectoderm gives the skin and nervous system, while mesoderm forms muscle, bone, and the circulatory system. The coelom, meanwhile, is a body cavity that arises within mesoderm, not a germ layer itself.