[The level of chromosomal DNA methylation in mice in the early stages of embryogenesis studied by the action of restriction endonucleases on the chromosomes].

The degree of genome methylation was estimated on chromosomal slides of mouse zygotes, morulae and embryos of 10 day of gestation using in situ digestion with restriction endonucleases MspI and HpaII. The chromosome preparations of all the embryo stages were made by the same method. The degree of methylation was evaluated by the appearance of chromosomes after digestion and by staining with the Giemsa stain. At the zygote stage, both maternal and paternal genomes are more methylated than chromosomes of the next stages of development. The paternal genome is more methylated than maternal. The homologous chromosomes of morulae and 10 day embryos were identical and the pattern of G-banding was formed.