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Q.
Grey crescent is the area
JIPMERJIPMER 2013Structural Organisation in Animals
Solution:
In ovum of some amphibians, about ten minutes after the penetration of sperm, the yellow cortical ooplasm of the egg starts flowing towards the sperm entrance. At the future dorsal side, the cytoplasm moves towards the animal pole, and at the opposite side (the future ventral side) it moves towards the vegetal pole. This exposes a lightly pigmented crescent-shaped area of marginal cytoplasm on the dorsal side, exactly opposite the point of sperm entrance. This is known as grey crescent.