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Yiyan Wang, Fenfen Chen, Leping Ye, Barry Zirkin, and Haolin Chen

essential for spermatogenesis. TS also is important for the maintenance of secondary sexual functions. A number of longitudinal studies have shown that in most men there is a slow decline in serum levels of total and bioactive TS with aging, beginning at

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Selena U Park, Leann Walsh, and Karen M Berkowitz

oocytes impact reproductive potential and aging ( Tal & Seifer 2017 , ASRM 2020 ). Despite the widely accepted dogma that the oocyte pool is determinate, some reports suggest that new oocytes can form and contribute to the ovarian reserve ( Johnson et al

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Na Liu, Yan-Guang Wu, Guo-Cheng Lan, Hong-Shu Sui, Li Ge, Jun-Zuo Wang, Yong Liu, Tian-Wu Qiao, and Jing-He Tan

-dependent process of aging ( Yanagimachi & Chang 1961 , Whittingham & Siracusa 1978 ). This process of oocyte aging has been found to be always associated with a decrease in the MPF activity ( Xu et al . 1997 , Abbott et al . 1998 , Miao et al . 2005

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Margaret L Walker, Daniel C Anderson, James G Herndon, and Lary C Walker

Introduction Squirrel monkeys ( Saimiri sciureus ) are small New World primates with a maximum lifespan of ∼30 years ( Helvacioglu et al . 1994 ). Female squirrel monkeys reach reproductive maturity between 2.5 and 3.5 years of age ( Taub 1980

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Mia S Olesen, Anna Starnawska, Jonas Bybjerg-Grauholm, Alexandra P Bielfeld, Inge Agerholm, Axel Forman, Michael T Overgaard, and Mette Nyegaard

increasing number of women postpone their motherhood ( Baird et al. 2005 , Schmidt et al. 2012 ), it is becoming increasingly important to have a tool that can assess biological age in terms of fertility prognosis ( Alviggi et al. 2009 ). Recently

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K Grace Foley, Michele T Pritchard, and Francesca E Duncan

natural killer cells and proinflammatory cytokines likely released by macrophages ( Weiskopf et al. 2009 ). The increasing levels of innate immune activity can become pathogenic and lead to an acceleration of normal aging. This chronic, sterile, low

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Maria Kokkinaki, Tin-Lap Lee, Zuping He, Jiji Jiang, Nady Golestaneh, Marie-Claude Hofmann, Wai-Yee Chan, and Martin Dym

Introduction Age has a deleterious effect on most tissues and organs, eventually leading to system failure. However, the mechanisms of aging in the various systems have been difficult to investigate and fully comprehend. Although men appear to be

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Weiling Yin and Andrea C Gore

Overview of reproductive senescence in female mammals Aging of the female reproductive system involves all three levels of the reproductive axis, comprising the brain, pituitary and ovary. Most research on the mechanisms of menopause

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Zijing Zhang, Florencia Schlamp, Lu Huang, Haley Clark, and Lynae Brayboy

pursuing their aspirations. However, it is a long-known fact that the female fertility decreases with chronological age and ultimately diminishes when women reach menopause in their fifties. At advanced reproductive age, pregnancies are not only harder to

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Ruiying Diao, Kin Lam Fok, Li Zhao, Hao Chen, Hui Tang, Jing Chen, Aiping Zheng, Xiaohu Zhang, Yaoting Gui, Hsiao Chang Chan, and Zhiming Cai

Introduction The effect of aging on fertility has become an important problem in public health due to the delayed marriage and parenthood in the modern world. Age-dependent decline in female fertility is well defined to be associated with the