Abstract
Germ cells are highly specialized cells that form gametes, and they are the only cells within an organism that contribute genes to offspring. Germline stem cells (GSCs) sustain gamete production, both oogenesis (egg production) and spermatogenesis (sperm production), in many organisms. Since the genetic information contained within germ cells is passed from generation to generation, the germ line is often referred to as immortal. Therefore, it is possible that germ cells possess unique strategies to protect and transmit the genetic information contained within them indefinitely. However, aging often leads to a dramatic decrease in gamete production and fecundity. In addition, single gene mutations affecting longevity often have a converse effect on reproduction. Recent studies examining age-related changes in GSC number and activity, as well as changes to the stem cell microenvironment, provide insights into the mechanisms underlying the observed reduction in gametogenesis over the lifetime of an organism.
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Acknowledgements
The author would like to thank Thomas Flatt, Andrew Dillin, Shawn Ahmed, and Matt Wallenfang for helpful discussions and comments on the manuscript and acknowledges support from the Ellison Medical Foundation, the American Federation for Aging Research, the G. Harold and Leila Y. Mathers Charitable Foundation, and NIH/NIA grant R01 AG028092 (D.L.J.). I apologize to those colleagues whose work has not been referenced directly due to space limitations.