The Sex Ratio Before Uterine Implantation in the Golden Hamster

Abstract

ABSTRACT Blastocysts from the golden hamster have been sexed at 3·5 days after mating, i.e. before implantation, by analysing metaphase plates for the presence of XX or XY chromosomes. Out of 98 embryos sexed, 63 were males and 35 females, giving a sex ratio of 180:100; this significantly deviates from a ratio of 1:1 (X2 = 8·00, p < 0·01). The sex ratio among 167 young of the golden hamster was found to be 106:100. Some possibilities for the origin of this high sex ratio in early stages is discussed.