Chromosome abnormalities in rabbit preimplantation blastocysts induced by superovulation

Abstract

The authors studied the result of superovulation induced by gonadotrophins on the karyological constitution of preimplantation rabbit blastocysts. Nine female rabbits were mated to fertile males 4 days after receiving pregnant mare serum gonadotrophin, and immediately prior to an injection of human chorionic gonadotrophin. Six female controls received saline injections. At 5-7 days of pregnancy intact blastocysts were recovered by flushing the uterine horns. No chromosomal abnormalities were found in the animals' leukocytes. The experimental group yielded 7 chromosomally abnormal blastocysts (9.7%); 3 triploids, 1 mosaic, 1 monosomy, 1 trisomy, and 1 sex chromosome chimera, whereas the controls' blastocysts were all normal. The anomalies are described in detail, the literature is discussed, and it is stated that blastocysts obtained after superovulation are not suitable test subjects for many types of reproduction studies, since possible genetic effects of the superovulation have to be considered. (Rohan - Roznov)