Crossword clues for pronucleus
The Collaborative International Dictionary
Pronucleus \Pro*nu"cle*us\, n.; pl. Pronuclei (-[imac]). [NL. See Pro-, and Nucleus.] (Biol.) One of the two bodies or nuclei (called male and female pronuclei) which unite to form the first segmentation nucleus of an impregnated ovum.
Note: In the maturing of the ovum preparatory to impregnation, a part of the germinal vesicle (see Polar body, under Polar) becomes converted into a number of small vesicles, which aggregate themselves into a single clear nucleus. which travels towards the center of the egg and is called the female pronucleus. In impregnation, the spermatozo["o]n which enters the egg soon loses its tail, while the head forms a nucleus, called the male pronucleus, which gradually travels towards the female pronucleus and eventually fuses with it, forming the first segmentation nucleus.
Wiktionary
n. Either of the two haploid nuclei (of a sperm and ovum) that fuse during fertilization
WordNet
n. the nucleus of the ovum or sperm after fertilization but before they fuse to form the nucleus of the zygote
[also: pronuclei (pl)]
Wikipedia
A pronucleus (plural: pronuclei) is the nucleus of a sperm or an egg cell during the process of fertilization, after the sperm enters the ovum, but before they fuse. Sperm and egg cells are haploid, meaning they carry half the number of chromosomes. The male and female pronuclei don't fuse, although their genetic material does. Instead, their membranes dissolve, leaving no barriers between the male and female chromosomes. Their chromosomes can then combine and become part of a single diploid nucleus in the resulting embryo, containing a full set of chromosomes.
The appearance of two pronuclei is the first sign of successful fertilization as observed during in vitro fertilisation, and is usually observed 18 hours after insemination or ICSI. The zygote is then termed a two-pronuclear zygote (2PN). Two-pronuclear zygotes transitioning through 1PN or 3PN states tend to develop into poorer-quality embryos than ones who remain 2PN throughout development, and may be significant in embryo selection in IVF.
Usage examples of "pronucleus".
And in the wondrous alchemy that governs our existence, the successful suitor had been transformed into what is known as the male pronucleus.
The pronuclei were three-quarters ours — the rules for Juxt One are a bit more relaxed.