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 (prō-no͞o′klē-əs, -nyo͞o′-)
n. pl. pro·nu·cle·i (-klē-ī′)
The haploid nucleus of a sperm or egg before fusion of the nuclei in fertilization.

pro·nu′cle·ar adj.


n, pl -clei (-klɪˌaɪ)
(Biology) the nucleus of a mature ovum or spermatozoan before fertilization
pronuclear adj


(proʊˈnu kli əs, -ˈnyu-)

n., pl. -cle•i (-kliˌaɪ)
the haploid nucleus of either the sperm or ovum that unites with the opposite-sex nucleus during fertilization.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.pronucleus - the nucleus of the ovum or sperm after fertilization but before they fuse to form the nucleus of the zygote
cell nucleus, karyon, nucleus - a part of the cell containing DNA and RNA and responsible for growth and reproduction
References in periodicals archive ?
The first step in confirming a successful fertilization is determining the number and shape of the pronuclei (PN).
Fertilisation was accepted as the presence of two pronuclei. Quality of embryos were assessed under invert microscopy on day 3, when at least 8-cell stage, according to their morphological characteristics and classified from best quality Grade 1 to poor quality Grade 3.
Then, two rounds of injection of both mRNA of TALEN and circular targeting template were made into pronuclei of fertilized mouse oocytes.
After 18-20 h observation, fertilization was determined by the presence of pronuclei. The zygotes were transferred to drops of G-1 (Vitrolife, Sweden) for culture.
Oocytes were considered successfully fertilized when two pronuclei were observed 1 day later.
Hence, the formation of female pronucleus and fusion of the male and female pronuclei did not occur.
This rat model was generated on a Fischer 344 background by co-injecting rat pronuclei with two mutant human genes (APPsw and PS1?E9) driven by the mouse prion promoter.
The presence of two pronuclei in the absence of sperm head within the oocyte or perivitelline space was an indication of the presence of both female and male pronuclei.
The incompatible cross, due to the asynchrony of the male and female pronuclei phases at the initial stage of mitosis, occurs when Wolbachia-infected males mate with uninfected females (unidirectional CI).
Caption: Two parental pronuclei in a newly fertilized human egg.
Fertilization was confirmed 17-20 h after insemination by the presence of a fertilized oocyte with two pronuclei. Embryos were monitored for cell number and morphological quality [1 (best) to 5 (worst)] on days 2 and 3, and considered of best quality if they had a score of 1 or 2.