[New methodologic approaches and perspectives in experimental cytogenetics of embryonic mammalian development].

When using heterozygotic carries of reciprocal or Robertsonian translocations and new methods permitting to identify homologous chromosomes in the karyotype, it is possible to obtain mouse embryos with trisomy and monosomy of any of the autosomes. This allows to analyze the effect of excess or deficiency of genetic material concerning definite linkage groups on morphogenetic processes. The cleavage and formation of blastocyst are not controlled by the zygote chromosomes; beginning from the late blastocyst stage in Muridae all or almost all autosomes display the functional activity. At these stages embryos with monosomy are eliminated whereas the embryos with autosome trisomy survive till later stages. No dependence was found between the time of embryonic death and the size of autosome in excess. The importance of data obtained by means of new methods of cytogenetic analysis is discussed.