Pronucleus


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Related to Pronucleus: Female pronucleus

pronucleus

[prō′nü·klē·əs]
(cell and molecular biology)
One of the two nuclear bodies of a newly fertilized ovum, the male pronucleus and the female pronucleus, the fusion of which results in the formation of the germinal (cleavage) nucleus.

Pronucleus

 

the haploid nucleus of a sex cell, or gamete. During fertilization, the diploid nucleus of the zygote, or synkaryon, is formed by the fusion of two pronuclei; the chromosome sets of both pronuclei are joined in the synkaryon.

In multicellular organisms and a number of protozoans that are anisogamous, there are female and male pronuclei. The female pronucleus is the nucleus of a mature egg cell, or macro-gamete. The male pronucleus is formed by the swelling of the nucleus of a spermatozoid, or microgamete, after it has become embedded in the cytoplasm of an egg cell. In isogamous unicellular organisms, the fusing pronuclei, like the gametes themselves, are morphologically indistinguishable. During autogamy, pronuclei that have been formed in the same cell fuse; they are usually sister nuclei. During conjugation in infusorians, two pronuclei form in each partner—a stationary pronucleus and a migrating pronucleus. There is first an exchange of migrating pronuclei between partners through a cytoplasmic bridge, which is followed by the fusion of the pronuclei in each of the partners.

References in periodicals archive ?
The male pronucleus condensed and remained quiescent until PB2 extrusion in the egg cytoplasm, at which point it began to swell.
Separation of a pronucleus by premature cytokinesis: a mechanism for immediate diploidization of tripronuclear oocytes?
In vitro maturation of bovine cumulus-oocyte complexes in undiluted follicular fluid: effect on nuclear maturation, pronucleus formation and embryo development.
Oocytes with one pronucleus and a non-decondensed sperm head were considered activated, and those with two pronuclei and without a non-decondensed sperm head were considered fertilized.
As this occurs a new nuclear envelope organizes to form the male pronucleus.
Copies of the promoter and foreign gene construct are microinjected directly into the male pronucleus with a fine glass needle.
After confirming that the ovum has reached the stage where it can allow fertilization, he removes the donor's sperm cells, which by then are in a pronucleus state.
Examination of the transparent eggs of Beroe revealed that several sperm typically penetrate the ovum (polyspermy) and that the female pronucleus then moves around within the ovum to each of the male pronuclei in turn before fusing with one of them.
The hydatidiform mole is a uterine tumor that occasionally develops in which the fetus is absent and the placental tissue is abnormally large, arising most often from a sperm's fertilizing an ovum in which the female pronucleus is absent.
The egg membranes and membrane of one pronucleus are pierced, and the gene replicas are placed inside the pronucleus.
2010), and Tet 3 is highly expressed in both oocyte and zygote, being responsible for 5-hmc increase on paternal pronucleus, while the maternal genome is protected by binding to PGC7 protein (also known as Dppa3 or Stella) (IQBAL et al.