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One of the two bodies or nuclei (called male and female pronuclei) which unite to form the first segmentation nucleus of an impregnated ovum.

The egg-nucleus or sperm-nucleus during fertilization.

Nucleus of the egg-element (female, p.) or of the sperm-element (male, p.) after the coalition of the spermatozoon with the ovum.

A primordial or germinal nucleus.