[Effect of structural aberrations in chromosomes 7 and 14 on the embryogenesis of laboratory mice]

A cytogenetical analysis of the oocytes and embryos at different developmental stages was carried out in mice heterozygous by the unequal reciprocal translocation T (7; 14) 2 IEM and their fecundity was studied. In heterozygotes this translocation leads to semisterility of both females and males which is due to structural aberrations of the chromosomes arising in meiosis. The duplication of a distal region of the chromosome 7 (Dp7F4) combined with the deletion of almost the whole chromosome 14, except its pericentromere region (Df14BCDE) did not affect cleavage and implantation but arrested the development at the early neurula stage and caused the death of embryos in the period of active organogenesis. The deletion of a distal region of the chromosome 7 (Df7F4) combined with the duplication of the chromosome 14 (Dp14BCDE) affected already the cleavage stages and caused the death of embryos at the blastocyst stage. A partial trisomy of the chromosomes 7 and 14 (Tc14(7)T(7;14)2 IEM) did not affect the development until the beginning of placentation. A conclusion is drawn on the important role of the distal region of the chromosome 7 (7F4) in the realization of preimplantation developmental stages in laboratory mice and possible causes of this phenomenon are discussed.