Cytogenetics of preimplantation embryos produced by pigs heterozygous for the reciprocal translocation (4q+;14q-).

The karyotype of embryos and newborns produced by pigs heterozygous for the reciprocal translocation rep(4q+;14q-) were studied. Forty-seven 9- to 10-day-old embryos were recovered. Only 27 (57.3%) could be karyotyped. Of these, 16 (59.3%) had normal or balanced heterozygous karyotypes, and 11 (40.7%) had unbalanced ones. Six different types of unbalanced karyotypes were identified. No unbalanced karyotypes was found in 38 newborn piglets produced by five heterozygous animals. It was concluded that unbalanced karyotypes are lethal at the embryonic stage.