Question

All are derived from ectoderm except -

• A. Hypophysis
• B. Retina
• C. Spinal cord
• D. Adrenal cortex

Hint:

Adrenal cortex is mesoderm; only the adrenal medulla is neural crest (ectoderm).

Answer 1

The Correct Option is D

Step 1: The question asks which structure is NOT derived from ectoderm. We assess the germ-layer origin of each option.

Step 2: The adrenal cortex arises from the coelomic epithelium, which is mesoderm. In contrast, the adrenal medulla (chromaffin cells) comes from neural crest cells (ectoderm). So the cortex is the mesodermal exception.

Step 3: Why the others are ectodermal - the hypophysis (pituitary) has an anterior lobe from the surface ectoderm of the oral cavity (Rathke's pouch) and a posterior lobe from neural ectoderm of the hypothalamus. Both spinal cord and retina develop from neural ectoderm (the neural tube and optic vesicle respectively).

Step 4: Therefore the adrenal cortex is the only mesodermal structure and is the correct answer.