The process of cleavage could be noticed to be operative in animal eggs, only in the eighteenth century, when, in year 1738 first of all Swammerdam observed the first cleavage of the frog’s egg. In 1780, Spallanzani described first two cleavage planes of egg. Prevost and Dumas in 1824, made extensive observations on the cleavage of the eggs of frog. Their work is followed by other embryologists and cleavage studies of eggs of frogs, newts, coelenterates, nematodes, and starfishes, were made. The first reported cleavage of the eggs of a rabbit was made in 1838-1839; a fish in 1842 and a several aspects of cleavage more understandable.