Transport of organelles along microtubules is essential for the cell metabolism and morphogenesis. The presented analysis derives the probability that an organelle of a given size comes in contact with the microtubule aster. The question is asked how this measure of functionality of the microtubule aster is controlled by the centrosome. A quantitative model is developed to address this question...

We demonstrate the presence of centrioles in fertilized human oocytes at syngamy. Single or double centrioles within centrosomes were detected by transmission electron microscopy at one pole of the first cleavage spindle in normal and dispermic embryos (25-26 hr after insemination). Sperm centrioles were also closely associated with the male pronucleus (16-20 hr after insemination) in pronuclea...

To complete meiosis II in animal cells, the male DNA material needs to meet the female DNA material contained in the female pronucleus at the egg center, but it is not known how the male pronucleus, deposited by the sperm at the periphery of the cell, finds the cell center in large eggs. Pronucleus centering is an active process that appears to involve microtubules and molecular motors. For sma...

Cells originating from the thymus of newborn mice were fused with mouse oocytes using polyethylene glycol. The behaviour of thymocyte nuclei was studied in non-activated metaphase II oocytes, and in oocytes activated in vitro with ethanol. In non-activated oocytes all thymocyte nuclei undergo premature chromosome condensation with individualization of chromosomes; the chromosomes form separate ...

Rabbit oocytes from preovulatory follicles resume meiosis up to metaphase II in normal delay when cultured in TC 199 supplemented with rabbit and calf sera and chick embryo extract. They are fertilizable, but such oocytes are unable to assume transformation of the sperm head into a normal nucleus, the male pronucleus. Rabbit preovulatory follicle can be maintained in healthy conditions for at l...

In many animal species, the sperm DNA is packaged with male germ line--specific chromosomal proteins, including protamines. At fertilization, these non-histone proteins are removed from the decondensing sperm nucleus and replaced with maternally provided histones to form the DNA replication competent male pronucleus. By studying a point mutant allele of the Drosophila Hira gene, we previously s...

We have investigated the development of reconstituted embryos in which enucleated 1- or 2-cell embryos received various advanced nuclei. Enucleated 1-cells developed to the blastocyst stage only when an early 2-cell donor nucleus was transferred but very rarely if the donor nucleus was derived from a late 2-cell, early 4-cell or mid 8-cell embryo. Although an 8-cell nucleus could only support d...

Unfertilized mouse eggs were activated in vitro with hyaluronidase. Subsequently they were exposed to culture medium at different osmolarities. In full strength White's culture medium they tended to form one pronucleus and a second polar body. The majority of these eggs were haploid. In 4/5 and 3/5 dilutions of this medium, the second polar body formation was suppressed and eggs tended to form ...

Bovine oocytes matured in vitro were stimulated by a single pulse of direct current (DC), then cultured for 0.5-6 h and evaluated by light (LM) and transmission electron microscopy (TEM). At the light microscopic level, the beginning of oocyte chromatin decondensation was first observed 3 h post-activation (14%). A well-developed pronucleus with evenly granulated nucleoplasm surrounded by nucle...

The CRISPR/Cas system, in which the Cas9 endonuclease and a guide RNA complementary to the target are sufficient for RNA-guided cleavage of the target DNA, is a powerful new approach recently developed for targeted gene disruption in various animal models. However, there is little verification of microinjection methods for generating knockout mice using this approach. Here, we report the verifi...