THE CHROMOSOME COMPLEMENT OF RABBIT BLASTOCYSTS IN RELATION TO THE TIME OF MATING AND OVULATION

Abstract

Six-day blastocysts were recovered from rabbits mated at various intervals from 0 to 10 hours after an ovulation-inducing injection of chronic gonadotrophin. Ten of eighty or 13% of the blastocysts from animals mated between 6 and 9 hours after injection were triploid in chromosome constitution. When karyotyped, seven of the triploids had an XXY and three an XXX sex chromosome complex. The incidence of chromosome abnormalities at delay intervals from 0 to 4 hours was 5%, approximately. No triploids were found at these times. The sex chromosome complex of 6-day blastocysts was XY in 54% and XX in 46% of the blastocysts. No difference in the sex ratio was noted with delayed mating.