Stem cells giving rise to extraembryonic tissues.

The review is devoted to characterization of stem cells involved in the formation of extraembryonic tissues during the early development of mammalian embryos. Here we present our results of characterization of stem cells from the trophoblast and extraembryonic endoderm of voles and comparative analysis of these cells and the corresponding mouse cells and discuss possible signal pathways maintaining these cells in undifferentiated state.

[Modifications in major satellite methylation in the nucleus of a two-cell mouse embryo dependent on developmental conditions].

The study of the degree of DNA methylation in the nucleus, in particular of the major satellite in two-cell mouse embryos developing in the maternal organism, in standard cultural media M16 used for cultivation of mouse embryos and M2 media used for manipulations with embryos in the air was conducted. Two-cell embryos nucleus aged 44-46 hours after chorionic hormone injection were investigated. The revealed results are evidence for the dependence of the major satellite Ts methylation level of the developmental conditions of embryos.

FGF4 independent derivation of trophoblast stem cells from the common vole.

The derivation of stable multipotent trophoblast stem (TS) cell lines from preimplantation, and early postimplantation mouse embryos has been reported previously. FGF4, and its receptor FGFR2, have been identified as embryonic signaling factors responsible for the maintenance of the undifferentiated state of multipotent TS cells. Here we report the derivation of stable TS-like cell lines from the vole M.

[Localization of satellite DNA and associated protein in respect to nucleolar precursor bodies in one- and two-cell mouse embryos].

Nucleolar precursor bodies (NPB) are characteristic structures in the nuclei of one- and two cell mouse embryos. The alignment of centromeric (CEN) and pericentromeric (periCEN) chromosome regions to the chromatin layer surrounding NPB is known. Mus musculus 4 satellite DNA (satDNA) types are known to be located in CEN region--mouse minor satellite (MiSat) and mouse satellite 3 (MS3); and periCEN region--mouse major satellite (MaSat) and mouse satellite (MS4).

[The study of preimplantation development of mice embryos labelled with green fluorescent protein gene (EGFp)].

One of the crucial problems of developmental biology is the study of mechanisms of regulation of gene expression in early embryogenesis. Here we studied dynamics of mosaic appearance of a marker fluorescent protein in in vitro developing mice embryo derived from zygotes after microinjections to male pronuclei of cloned DNA fragment carrying EGFP under control of different promoters. Main attention was paid to initial stages of development, when structural rearrangements and reprogramming of both parental genomes, activation of zygotic genes, and control of development by embryo genome take place.