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: Group the choices by their developmental source. Three of them trace back to the neural plate or oral ectoderm, while one is suprarenal cortical tissue with a separate lineage.

Step 2: Neural ectoderm gives rise to the brain and spinal cord, and also to the retina via the optic vesicle outgrowth of the diencephalon. The pituitary is a dual ectodermal organ - its pars distalis buds from Rathke's pouch (surface ectoderm) and its pars nervosa descends from neural ectoderm.

Step 3: The suprarenal gland is the key trap. Its outer cortex develops from the urogenital ridge mesoderm (coelomic epithelium), whereas only its inner medulla is neural-crest (ectodermal). Since the question names the cortex, the answer is mesodermal in origin.

Step 4: Hence the structure that is not ectodermal is the adrenal cortex.

\[\boxed{\text{Adrenal cortex (mesoderm)}}\]