Crossword Dictionary

What's The Definition Of 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.