Effects of aging on male fertility?

The increase in male life expectancy has raised issues concerning the impact of aging on the endocrine system and male fertility. This review focuses on the relationship of spermatogenesis to changes with age in androgen production and testicular morphology, the influence of age on semen parameters and chromosomal quality, and the impact of paternal age and pregnancy outcome. While age-related endocrine changes are well documented, those concerning semen parameters and consequent fertility are based on cross-sectional studies alone. Nevertheless, characteristic age-related morphological testicular alternations have been described, such as decreased numbers of Leydig cells paralleling decreased testosterone production, arteriosclerotic lesions, thickening and hernia-like protrusions of the basal membrane of the seminiferi tubules, and fibrotic thickening of the tunica albuginea. Surprisingly, these alterations do not lead to significant differences in sperm-morphology, time of spermatozoa development or sperm function between young and elderly males. Reports on decreased sperm motility, semen volume and changes in sperm count are contradictory. Although numerical chromosomal abnormalities of spermatozoa are not higher in aging males, an increase in structural aberrations can be observed. Consequently, children of elderly fathers show a 20% higher risk for autosomal dominant diseases, presumably due to increasing numbers of germ cell meioses and mitoses. Thus, the American Fertility Society recommends an age limit for semen donors of 50 years or less.