Pronucleus

[prәu'nju:kliәs]

(noun.) the nucleus of the ovum or sperm after fertilization but before they fuse to form the nucleus of the zygote.

Checked by Laurie--From WordNet

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

Edited by Ethelred