Cleavage
The cleavage occurs more readily in the active cytoplasm than the yolk-laden cytoplasm or deutoplasm of the egg. The yolk which occurs in all animal eggs in little (e.g., microlecithal eggs) or larger (e.g., mesolecithal and macrolecithal eggs) amounts and remains distributed evenly (e.g., isolecithal eggs) or unevenly (e.g., telolecithal eggs) in the ooplasm of [...]
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 [...]
This is the inherent nature of the sexually reproductive multi-cellular animals that their body originates from a large-sized, single celled (unicellular), nutrient-filled, diploid and fertilized egg or zygote. In them, immediately after the activation of egg either through the intervention of a spermatozoon (fertilization) or through some parthenogenetic agent (parthenogensis), the activated egg is passed [...]
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