Aging and Male Reproduction

Histological changes

Reference

Physiological germ cell loss, Leydig cell loss

Holstein (1989)

Reduced dark A spermatogonia, giant spermatids, multinucleated spermatogonia

Johnson et al. (1990)

Lipid droplets in Sertoli cells, megalospermatocytes

Harbitz (1973)

Tubule involution

Panigua et al. (1987)

Defective vascularization of testicular parenchyma

Regadera et al. (1985)

The defective vascularization of testicular parenchyma is associated with systemic arteriosclerosis of the aging man.

13.6 Aging and Semen Parameters

Bearing in mind the various age-dependant changes taking place in the reproductive organs of men, expecting a high degree of variance in semen parameters is not surprising. Studies that have explored the effect of age on semen parameters are summarized in Table 13.2 below.

Table 13.2

Studies mentioned in the table show the possible association of aging and it’s impact on semen parameters

Study	No	Age	Effect on volume	Effect on concentration	Effect on motility	Effect on morphology
Studies on proven fertile males including sperm donors
Dondero et al. (1985)	445	18–81	↓ NS after 40 years	↓ NS after 40 years	↓ NS after 40 years	No effect
Homonnai et al. (1982)	555	20–68	30 % decrease	No effect	↓ significant	No effect
Nieschlag et al. (1982)	43	24–88	↓ NS	Significant	↑ significant	No effect
Wang et al. 1985	1239	19–53	No effect	No effect	No effect	No effect
Bujan et al. (1996)	302	21–44	No effect	↑ 3.3 % per year but NS	No effect	No effect
Irvine et al. (1996)	577	18–53	No effect	↑ 2.1 % per year but HS	No effect	No effect
Eskenazi et al. (2003)	97	22–80	↑ 0.03 ml per year	↓ 2.5 % per year but significant	No effect	No effect
Fisch et al. (1996)	1283	34.3	R = 0.15, weak effect	R = 0.03, no effect	NS	No effect
Auger et al. (1995)	1351	19–59	No effect	↓ 3.3 % per year but NS	↓ 0.6 % per year	No effect
Schwartz et al. (1983)	809	26–50	No effect	No effect	↓ NS	↓ 0.9 % per year
Studies on men with infertility
Mladenovic et al. (1994)	77	20–50	No effect	No effect	↓ significant	↓ significant
Berling and Wolner (1997)	718	21–54	No effect	No effect	No effect	No effect
Andolz et al. (1999)	20,411	15–74	↓ 0.5 % per year	↑ 0.7 % per year	↓ 0.3 % per year	↓ NS
Spandorfer et al. (1998)	821	39–50	NS	No effect	↓ NS	No effect
Rolf et al. (1996)	117	22–61	HS	↑ NS	↓ significant	No effect
Rolf et al. (2002)	3437	19–63	HS	No effect	No effect	No effect
Henkel et al. (1999)	90	22–57	No effect	No effect	No effect	No effect
Centola and Eberly (1999)	2065	19–67	↓ NS	No effect	No effect	↓ NS

↑ depicts an increase, ↓ depicts a decrease. NS non significant, HS highly significant

Most of the studies exploring the effect of age on semen parameters are limited in their ability to determine a suitable effect, as most of these studies are based on retrospective data further limited by a small sample size. To summarize the outcome of these studies, it would seem that the effect of aging on semen parameters is variable; no conclusion should be drawn in light of present evidence. Although a small effect is noted in different studies, the parameters measured were still within the normal reference ranges used in the studies. No threshold age is seen beyond which a rapid decline in semen parameters occurs. Much larger studies accounting for the inherent variability of semen parameters are required to come to any meaningful conclusions.

13.7 Effect of Paternal Aging on Genetics

Early observations have suggested that increasing male age is associated with certain syndromes. A possible reason is that, in males, there are a net higher number of germ cell divisions as compared to females, and male germ cells divide almost continuously (Crow 2000). Bearing in mind this association, the age of semen donors in some countries has been capped at 40 years (ASRM 1998). No effect of age on aneuploidies of chromosomes 6, 8, 12, 13, 14, and 18 has been observed from previous studies. A paternal age effect on disomies XX, XY, or YY has been observed in a few studies (Asada et al. 2000; Lowe et al. 2001). No paternal age effect for Turner’s syndrome as well as trisomy 13, 16, 18, and 21 (Hatch et al. 1990) is seen. However, larger studies clearly seem to show some effect as far as Down’s syndrome is concerned, especially when combined with advanced maternal age >35 years (Fisch et al. 2003).

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