EGGS OF FROG
This egg is round & its diameter is of 1-2 mm.
It is mesolecithal & has distinct animal pole & vegital pole.
The nucleus is found in the centre of the animal pole & it contains many nucleoli.
The animal pole is pigmented and the vegital pole is light yellow due to presence of the yolk.
The pigmented animal pole provides mimicry and contains melanin pigments.
The egg is covered by a vitelline membrane and jelly coats.
The jelly coats are tasteless & act as bacteriacidial. Hence, the jelly coats provide protection to the egg. The jelly coats keeps the eggs floating on the water.
The forg's egg develops a grey crescent after fertilization. The grey crescent is a future blastopore.