Question Detail
Question
The third cleavage in the development of frog is
Correct Answer
Option A is the correct answer.
Detailed Explanation
In frog (amphibian) development, cleavage is holoblastic (complete). The first two cleavages are vertical, dividing the egg into four equal blastomeres. The third cleavage is horizontal (equatorial), dividing the four cells into eight blastomeres. However, due to the yolk distribution, this cleavage is unequal, with the upper animal pole cells (micromeres) being smaller than the lower vegetal pole cells (macromeres). The correct description for the third cleavage is holoblastic and equatorial (horizontal).
Hint
Consider the orientation of the third cleavage division relative to the animal-vegetal axis.