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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 ?
Syngamy occurred as the swollen male and female pronuclei combined in the center of the egg, with the two centrosomes derived from the male pronuclei (Fig.
A difference was observed in time of pronuclei appearance, t8, t9+ cleavage times in time-lapse in the smoker and non-smoker groups (p<0.
The problem is that giant oocytes can develop either two or three pronuclei (PNi) after penetration of a spermatozoon, indicating that the abnormality might be overlooked if only the number of PNi is assessed and oocyte size is not taken into account.
Fertilization was confirmed 17-20 h after insemination by the presence of a fertilized oocyte with two pronuclei.
The IVF technique involves removing the pronuclei - the nucleus of the sperm and the egg during the process of fertilization - from an embryo containing the mother's unhealthy mitochondria.
Oocytes were examined under an optical microscope and classified as either (a) non fertilized: the presence of female and the absence of male chromatin; (b) normal fertilized: the presence of female and male chromatin in the cytoplasm, a decondensed sperm head, pronuclei or cleavage; (c) abnormal fertilized: asynchronous oocytes (marked alteration in the formation of pronuclei, as undecondensed sperm head or telophase II) and > 2 pronuclei (oocytes in which more than 2 pronuclei were observed in the cytoplasm); or (d) degenerate oocytes.
The fertilization rate was calculated as the number of oocytes with two pronuclei divided by the number of injected oocytes when ICSI was performed and by all intact oocytes retrieved when IVF was performed.
The fertilized oocytes with a second polar body or two pronuclei were removed and cultured in GM media (LGGG-50, LifeGlobal, Belgium) to the blastocyst stage for 4.
Although life is a continuous process, fertilization (which, incidentally, is not a 'moment') is a critical landmark because, under ordinary circumstances, a new genetically distinct human organism is formed when the chromosomes of the male and female pronuclei blend in the oocyte.
The fixed and stained structures were placed between slide and cover slip and exposed to UV light for visualization and counting of male and female pronuclei as well as first and second polar bodies.