[ proh-noo-klee-uh s, -nyoo- ]
/ proʊˈnu kli əs, -ˈnyu- /

noun, plural pro·nu·cle·i [proh-noo-klee-ahy, -nyoo-] /proʊˈnu kliˌaɪ, -ˈnyu-/. Cell Biology.

either of the gametic nuclei that unite in fertilization to form the nucleus of the zygote.

Origin of pronucleus

From New Latin, dating back to 1875–80; see origin at pro-1, nucleus Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for pronucleus


/ (ˌprəʊˈnjuːklɪəs) /

noun plural -clei (-klɪˌaɪ)

the nucleus of a mature ovum or spermatozoan before fertilization
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for pronucleus


[ prō-nōōklē-əs ]


One of two nuclei undergoing fusion in karyogamy.
The haploid nucleus of a sperm or egg before fusion of the nuclei in fertilization.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.