Pronucleus

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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.
     [1913 Webster]


  
     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 spermatozoon 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.
           [1913 Webster]

From WordNet (r) 2.0 [wn]:

  pronucleus
       n : the nucleus of the ovum or sperm after fertilization but
           before they fuse to form the nucleus of the zygote
       [also: {pronuclei} (pl)]