Diploid gynogenetic mouse embryos were produced in a three-step procedure: fertilization in vitro, suppression of the 2nd polar body formation by Cytochalasin B, and microsurgical removal of the male pronucleus. The operated eggs were transplanted to the oviduct of recipient females for 72 or 96 h. The overall recovery rate was 73%, but compacted morulae and blastocysts constituted only 28.6% o...

We find that the remodeling of the condensed Xenopus laevis sperm nucleus into the paternal pronucleus in egg extracts is associated with phosphorylation of the core histones H2A, H2A.X and H4, and uptake of a linker histone B4 and a HMG 2 protein. Histone B4 is required for the assembly of chromatosome structures in the pronucleus. However neither B4 nor core histone phosphorylation are requir...

In mammals, the sperm triggers a series of cytosolic Ca(2+) oscillations that continue for approximately 4 hours, stopping close to the time of pronucleus formation. Ca(2+) transients are also seen in fertilized embryos during the first mitotic division. The mechanism that controls this pattern of sperm-induced Ca(2+) signalling is not known. Previous studies suggest two possible mechanisms: fi...

MONG species of insects that have been used for genetic studies, there Aoccasionally appear adults which are composed of two or more different genomes. In Drosophila melanogaster, where most of these mosaics were of the gynandromorph type, it has been shown that elimination of an X chromosome during early cleavage was involved (MORGAN and BRIDGES 1919; PATTERSON 1931). In a few instances, ferti...

THE JOURNAL OF CELL BIOLOGY ° VOLUME 51, 1971 ° pages 579-583 nuclear membrane, and the intervening material is not uniquely structured although microtubules are frequently seen (4, 5) . In this paper, I have considered the possibility that the connection between the nucleus and the center is maintained by an aster-associated motile system. Astral ray-associated motility has been recognized for...

Failure of male pronucleus formation has hampered the success of intracytoplasmic sperm injection (ICSI) in swamp buffalo. The aim of the present study was to improve male pronucleus formation by pretreating sperm with various chemicals before ICSI. In Experiments1 and 2, sperm were treated according to one of the following protocols: (1) 0.1% Triton-X 100 (TX) for 1 min, (2) 10 μM calcium iono...

The assessment of oocytes showing only one pronucleus during assisted reproduction is associated with uncertainty. A compilation of data on the genetic constitution of different developmental stages shows that affected oocytes are able to develop into haploid, diploid, and mosaic embryos with more or less complex chromosomal compositions. In the majority of cases (~80%), haploidy appears to be ...

Fertilization events following coalescence of the gamete plasma membranes and culminating in the formation of the zygote nucleus were investigated by light and electron microscopy in the sea urchin, Arbacia punctulata. Shortly after the spermatozoon passes through the fertilization cone, it rotates approximately 180 degrees and comes to rest lateral to its point of entrance. Concomitantly, the ...

The number of sperm incorporated into eggs made polyspermic with varying concentrations of nicotine (0.025-0.25%, v/v) appears to be directly related to the concentrations employed. The cortical response is morphologically equivalent to that observed in control preparations. Shortly after their incorporation all of the spermatozoa undergo structural events normally associated with the developme...

Virginia were used. All these animals have similar micronuclei. During conjugation the pronuclei in the two conjugants are alike. Under such circumstances evidence of exchange of pronuclei was less convincing although there were many pairs in which an exchange evidently occurred. The migratory pronucleus was usually slender, the stationary pronucleus relatively short and broad. In many cases, t...