Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Optic grooves are primordia for ocular development.
Reason (R) : Optic groove appear at the end of neurulation prior to closure of the rostral neuropore.
In light of the above statements, choose the correct answer from the options given below

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true and (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

The first sign of the eye appears in the neural folds as the optic grooves around embryonic day 22 in humans (and corresponding early stages in domestic animals), before the neural tube is completely sealed.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Eye development begins very early in embryonic life with the appearance of localized depressions in the developing central nervous system, establishing the primordial coordinates for the future eyes.

Step 2: Detailed Explanation:
Let us analyze both statements and their relationship:
- Assertion (A):
The optic grooves (sulci) are the very first morphological indications of eye development.
They represent the anatomical primordia from which all neuroectodermal components of the eye (such as the retina, optic nerve, and iris epithelium) develop.
Therefore, Assertion (A) is correct.
- Reason (R):
During neurulation (the formation of the neural tube), the neural plate folds to form neural folds.
Just before the rostral (cranial) end of the neural tube closes (which occurs at the rostral neuropore), two small bilateral indentations appear on the inner surface of the forward-most neural folds (the future diencephalon).
These are the optic grooves.
Therefore, Reason (R) is correct.
- Relationship between (A) and (R):
The reason why these grooves are classified as the absolute primordia (earliest structures) of ocular development is because they are the first physical, morphologically distinct structures to appear during early neurulation before the neural tube has even completed its rostral closure.
Thus, (R) provides the temporal and structural explanation for why (A) is considered the earliest primordium.

Step 3: Final Answer:
The correct option is (A).