[Effect of monosomy of the autosomes on the preimplantation stages of embryogenesis in laboratory mice].

The effects of monosomy for the autosomes 1, 2, 3, 5, 6, 16 and 19 were studied in mice with single or double Robertsonian translocations. The monosomy for different autosomes affects the preimplantation development of the mouse embryos in different ways. The monosomy for the autosomes 1, 3, 6, 16 or 19 does not affect cleavage, compactization or blastulation and is, in some cases, even compatible with the implantation. The most these embryos are eliminated at the blastocyst stage (monosomy for the autosomes 3, 6 or 19) or, sometimes, at the postimplantation stages (1 or 16). The monosomy for the autosomes 2 or 5 is realized during cleavage causing the developmental delay, pathological changes in the nuclei of blastomeres and elimination at the morula stage. The results obtained suggest differential activity of chromosomes at the preimplantation stages of embryogenesis. Possible reasons for the early death of the embryos with particular types of monosomy are discussed. A hypothesis of mutual activation of the homologous autosomes at the early developmental stages is put forward. According to this hypothesis, the loci of a single unpaired autosome, especially of paternal origin, remain inactive during the early embryogenesis.