Effects of Aging of Sperm in the Female and Male Reproductive Tracts before Fertilization on the Chromosome Complement of the Blastocysts

Abstract

Literature on the effects of aging of sperm in the male or female reproductive tracts before fertilization on the chromosome complement of blastocysts of various non-human species especially the rabbit is reviewed. Polyploidy mixoploidy aneuploidy mosaics and structural anomalies have been observed as a result of the aging of sperm in cows pigs rabbits and mice. When sperm was aged in the reproductive tract of female rabbits there was a 9.9% incidence of chromosome anomalies such as chimerism mixoploidy and mosaics. The presence of chimeric blastocysts is attributable to dispermy involving the ovum pronucleus and the second polar body. The fertilization time-potential of rabbit spermatozoa in the female reproductive tract is about 30 hours. There was an 11% incidence of chromosome anomalies in blastocysts developing from oocytes fertilized by spermatozoa aged in the male reproductive tract. These abnormalities included triploidy mixoploidy and trisomy. The fertilization time-potential of spermatozoa in the male reproductive tract is about 4 weeks. It is concluded that aging of the male gamete may be an important factor in producing chromosomally abnormal embryos and zygotes.