Telomeres and Human Reproduction
Telomere dynamics differ between the female and male germ lines: oocytes have short telomeres, and their erosion recapitulates the reproductive aging phenotype, and telomere length in sperm increases with age.
Keri Horan Kalmbach, M.S., Danielle Mota Fontes Antunes, M.S., Roberta Caetano Dracxler, M.D., Taylor Warner Knier, B.A., Michelle Louise Seth-Smith, B.S., Fang Wang, Ph.D., Lin Liu, Ph.D., David Lawrence Keefe, M.D.
Volume 99, Issue 1, Pages 23-29, January 2013
Telomeres mediate biological aging in organisms as diverse as plants, yeast, mammals. We propose a Telomere Theory of Reproductive Aging that posits telomere shortening in the female germ line as the primary driver of reproductive aging in women. Experimental shortening of telomeres in mice, which normally do not exhibit appreciable oocyte aging, and which have exceptionally long telomeres, recapitulates the aging phenotype of human oocytes. Telomere shortening in mice reduces synapsis and chiasmata, increases embryo fragmentation, cell cycle arrest, apoptosis, spindle dysmorphologies and chromosome abnormalities. Telomeres are shorter in the oocytes from women undergoing IVF that go on to produce fragmented, aneuploid embryos and which fail to implant. In contrast, the testes are replete with spermatogonia that can rejuvenate telomere reserves throughout the life of the man by expressing telomerase. Differences in telomere dynamics across the lifespans of men and women may have evolved because of the difference in the inherent risks of aging on reproduction between men and women. Additionally, growing evidence links altered telomere biology to endometriosis and gynecological cancers, thus future studies should examine the role of telomeres in pathologies of the reproductive tract.