Question

In development, Eustachian tube is

• A. Ectodermal
• B. Mesodermal
• C. Endodermal
• D. Both Mesodermal and endodermal

Answer 1

Answer: (C)

Endodermal

The inner cell mass of the blastocyst after implantation differentiates into an outer ectoderm, middle mesoderm and inner endoderm. These layers then develop into tissues and organs of the embryo. Endoderm gives rise to certain organs including the colon, stomach, intestines, liver, lungs, middle ear and pancreas. Mesoderm gives rise to heart, kidneys, gonads, genital ducts, cartilage, muscles, blood cells, and other structures. Ectoderm forms the outer linings like the epithelium, brain, spinal cord, nerves, inner ear, nails and hair. The eustachian tube is part of the middle ear which is formed from the endoderm.

So the correct answer is C.