Testicular Aging: An Overview of Ultrastructural, Cellular, and Molecular Alterations

Abstract

The trend in parenthood at an older age is increasing for both men and women in developed countries, raising concerns about the reproductive ability and the consequences for the offspring's health. While reproductive activity in women stops with menopause, a complete cessation of the reproductive potential does not occur in men. Although several studies have been published on the effects of aging on semen parameters and spermatozoa DNA integrity, literature on impact of aging on the testis, particularly cellular and molecular alterations, has been, so far, limited and controversial. This work discusses the current knowledge on testicular aging in humans and other mammals, covering topics from tissue ultrastructure, to cellular and molecular alterations. Aging affects male reproductive function at multiple levels, from sperm production and quality, to the morphology and histology of the male reproductive system. The morphological and functional changes that occur in the testes result in variations in the levels of many hormones, changes in molecules involved in mitochondrial function, receptors and signaling proteins. Despite knowing that these age-related alterations occur, their real impact on male fertility and reproductive health are still far from being fully understood, highlighting that research in the field is crucial.

Cordycepin, an Active Constituent of Nutrient Powerhouse and Potential Medicinal Mushroom Cordyceps militaris Linn., Ameliorates Age-Related Testicular Dysfunction in Rats

“…Aging is involved in the degeneration of germ cells and Sertoli cells, reduction in sperm production, immaturity of spermatozoa, and decrease in seminiferous tubular size. Furthermore, histomorphological examination of the tubular cross sections of aged rats confirmed deficient spermatogenesis [1,33]. In agreement with the results of previous studies, our study showed reduced sperm motility, decreased seminiferous tubule size, and loss of sperm and Sertoli cell count per tubule in the AC group.…”

The hidden ageing costs of sperm competition

“…Overall, although there are several well‐understood aspects of male reproductive ageing, the extent to which a strong resource allocation to traits shaping sperm competition in early life amplifies ageing and thus exacerbates the widely observed decrease of the male gonadal size and function with increasing age (Lemaître and Gaillard, 2017; Fricke and Koppik, 2019; Santiago et al ., 2019) remains an open question. Answering it is of crucial importance, since such effects might not only reinforce male reproductive ageing (e.g.…”

TRPV1 Is Associated with Testicular Apoptosis in Mice

“…Various testicular changes occur in old mice, including the reduction of testicular volume (Gosden et al, 1982;Wolf et al, 2000), accumulation of lipofuscin (age pigment) in Leydig cells (Miquel et al, 1978), multiple alterations in the Sertoli cell population (Cummins et al, 1994), loss of germ cells, and molecular alterations (Santiago et al, 2019). Our study showed decreases in the diameter and volume of seminiferous tubules and the number of KO mice showed lower apoptosis in the testes than WT mice.…”