Frequency of chromosomally unbalanced gametes in male and female hamsters heterozygous for reciprocal translocation.

By using male and female Chinese hamsters heterozygous for reciprocal translocation, T(2;10) 3Idr and T(1;2)9Idr, features of metaphase II cells were observed, and the difference in frequency of each class of cells derived from quadrivalents was investigated. The result showed no difference between sexes in the segregation ratio of chromosomes from the quadrivalents in either strain. In four-day embryos from crosses between normal animals and translocation heterozygotes in both strains, the incidence of embryos with unbalanced chromosomes was significantly higher in the group from crosses between females heterozygous for the translocation and normal males than in the group from heterozygous males and normal females. These results suggest that in males unbalanced gametes are selectively eliminated during the period between the formation of gametes and fertilization.