The germ layer that forms the lining of the gut and the airways is which?

The germ layer that forms the lining of the gut and the airways is which?

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

Answer: (D)

Endoderm forms the interior linings of the gut and the airways. During gastrulation, this innermost germ layer gives rise to the epithelium lining the digestive tract and the respiratory tract, and it also forms many associated glands like the liver and pancreas. In contrast, ectoderm makes the outer skin and nervous system, and mesoderm builds muscles, bones, and the circulatory system. The coelom is a body cavity that develops within mesoderm, not a germ layer itself.

Endoderm forms the interior linings of the gut and the airways. During gastrulation, this innermost germ layer gives rise to the epithelium lining the digestive tract and the respiratory tract, and it also forms many associated glands like the liver and pancreas. In contrast, ectoderm makes the outer skin and nervous system, and mesoderm builds muscles, bones, and the circulatory system. The coelom is a body cavity that develops within mesoderm, not a germ layer itself.