Zygote

For other meanings see Zygote (disambiguation).

A zygote (from Greek zugōtos ‘joined’, from zugoun ‘to join’) is a cell that is the result of fertilization. That is, two haploid cells—usually an ovum from a female and a sperm cell from a male—merge into a single diploid cell called the zygote (or zygocyte).

In mammals, fusion of the sperm with the ovacyte occurs in the Fallopian tube and the resulting diploid zygote becomes embedded in the uterus wall.

Animal zygotes undergo mitotic cell divisions to become an embryo. Other organisms may undergo meiotic cell division at this time (for more information refer to biological life cycles).

Twins

Twins and multiple births can be monozygotic (identical) or dizygotic (fraternal), meaning they arise from one or several (strictly, two) fertilization events.

However, polyspermic zygotes in mice have been manipulated so as to remove one of the two male pronuclei and made to survive birth.

In other species

A biparental zygote is a Chlamydomonas zygote that contains chloroplast DNA (cpDNA) from both parents.

See also

• Sexual reproduction
• Zygote intrafallopian transfer
• Twin Zygosity

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