∞ generated and posted on 2015.12.28 ∞

Mitotic division during early animal embryonic development.

Cleavage is relatively unique among mitotic cell divisions in that cytokinesis is not followed by growth in cell volume but instead cleavage results in an embryo of approximately the same overall size as the originating zygote but consisting of numerous cells versus the single cell of the zygote.

Cleavage occurs with little cell growth between divisions, as the substantial volume of cytoplasm – and resulting skewed surface-to-volume ratio – is divided into individually smaller cytoplasmic volumes. Cleavage leads to formation of the morula.

Note that the pattern of cleavage differs between protostome and deuterostome animals. Protostomes display for example determinate cleavage while deuterostomes by contrast display indeterminate cleavage.

See also development and animal development.