polar nucleus

American  

noun

1. Botany.  either of two female haploid nuclei, in the embryo sac of flowers, that fuse to produce a diploid nucleus, which combines with a male nucleus to form the endosperm.

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Etymology

Origin of polar nucleus

First recorded in 1880–85

Example Sentences

One nucleus from each group, the polar nucleus, passes to the centre of the sac, where the two fuse to form the so-called definitive nucleus.

From Project Gutenberg

In two Malayan species of Balanophora, the embryo is developed from a cell of the endosperm, which is formed from the upper polar nucleus only, the egg apparatus becoming disorganized.

From Project Gutenberg

The signification of the coalescence of the polar nuclei is not explained by these new facts, but it is noteworthy that the second male-cell is said to unite sometimes with the apical polar nucleus, the sister of the egg, before the union of this with the basal polar one.

From Project Gutenberg