Polar body

First stages of segmentation of a mammalian embryo. Semidiagrammatic. z.p. Zona pellucida. p.gl. Polar bodies. a. Two-cell stage. b. Four-cell stage. c. Eight-cell stage. d, e. Morula stage.

A polar body is a small haploid cell that is formed at the same time as an egg cell during oogenesis, but generally does not have the ability to be fertilized. It is named from its polar position in the egg.

When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. Most of the cytoplasm is segregated into one daughter cell, which becomes the egg or ovum, while the smaller polar bodies only get a small amount of cytoplasm. They frequently die and disintegrate by apoptosis, but in some cases remain and can be important in the life cycle of the organism.^[1]

^ Schmerler, S.; G.M. Wessel (2011). "Polar bodies—more a lack of understanding than a lack of respect". Mol. Reprod. Dev. 78 (1): 3–8. doi:10.1002/mrd.21266. PMC 3164815. PMID 21268179.

[Schmerler-1] Schmerler, S.; G.M. Wessel (2011). "Polar bodies—more a lack of understanding than a lack of respect". Mol. Reprod. Dev. 78 (1): 3–8. doi:10.1002/mrd.21266. PMC 3164815. PMID 21268179.

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