Question

Glands of vertebrates have originated from

• A. Ectoderm
• B. Endoderm
• C. Mesoderm
• D. All of the above

Answer 1

Answer: (D)

All of the above

The zygote divides incessantly to form numerous cells which undergo gastrulation and forms three germ layers. In-growth from an epithelial surface leads to the formation of glands. This invagination starts after formation of germ layers. Endoderm also forms the lining cells of all the glands. The surface ectoderm develops into the epidermis, hair, nails, the lens of the eye, sebaceous glands, cornea, tooth enamel, the epithelium of the mouth and nose. The mesoderm forms adrenal glands.

So, the correct answer is option D.