Neaves W B, Johnson L, Porter J C, Parker C R, Petty C S
J Clin Endocrinol Metab. 1984 Oct;59(4):756-63. doi: 10.1210/jcem-59-4-756.
Age-related changes in Leydig cell number, daily sperm production, and circulating hormone levels were studied in 15 men between 20 and 48 yr of age and 15 men between 50 and 76 yr of age. Testes and blood samples were obtained at autopsy less than 15 h after death due to trauma or heart attack. Leydig cell number was determined by quantitative histometric estimation of the proportion of glutaraldehyde-perfused, decapsulated testicular parenchyma occupied by Leydig cell nuclei of measured average volume in both testes of each subject. Daily sperm production was determined by phase contrast cytometry of round spermatid nuclei in homogenates of both fixed testes from each individual. LH, FSH, PRL, and testosterone in serum from the heart or large veins were quantified by RIA. No relationship was detected between any of the testicular or hormonal values and postmortem time. The average total number of Leydig cells was reduced by 44% in the older men and was negatively correlated with age (p = -0.62) in all men. Mean serum LH was elevated more than 2-fold in the older men and was positively correlated with age (p = +0.53) in all men. Neither serum testosterone nor serum PRL changed significantly with age. Daily sperm production was more than 50% lower in older men and was negatively correlated with age (p = -0.76) in all men. Serum FSH was more than 3-fold higher in the older men and was positively correlated with age (p = +0.72) in all men. The highest FSH levels were found in men with the lowest rates of sperm production, and FSH and daily sperm production were inversely correlated even after the effects of age were removed. These findings show that the response of the human testis to aging is variable and that the predictive value of age for most testicular characteristics is weak at the level of individual men. Nevertheless, age accounts for more than a third of the variation in Leydig cell number, and it explains more than half the variation in daily sperm production. Hence, age is the largest single contributing factor yet identified in the search for explanations underlying the variation in testicular structure and function found in groups of normal men.
对15名年龄在20至48岁之间的男性和15名年龄在50至76岁之间的男性，研究了睾丸间质细胞数量、每日精子生成量及循环激素水平随年龄的变化。因外伤或心脏病发作死亡后，在尸检后不到15小时获取睾丸和血液样本。通过定量组织计量学估计戊二醛灌注、去包膜的睾丸实质中被每个受试者双侧睾丸中测量平均体积的间质细胞核所占比例，来确定间质细胞数量。通过对每个个体双侧固定睾丸匀浆中圆形精子细胞核进行相差细胞计数，来确定每日精子生成量。采用放射免疫分析法对心脏或大静脉血清中的促黄体生成素（LH）、促卵泡生成素（FSH）、催乳素（PRL）和睾酮进行定量分析。未检测到任何睾丸或激素值与死后时间之间存在关联。老年男性的间质细胞平均总数减少了44%，且在所有男性中与年龄呈负相关（p = -0.62）。老年男性的平均血清LH升高了2倍多，且在所有男性中与年龄呈正相关（p = +0.53）。血清睾酮和血清PRL均未随年龄发生显著变化。老年男性的每日精子生成量降低了50%以上，且在所有男性中与年龄呈负相关（p = -0.76）。老年男性的血清FSH升高了3倍多，且在所有男性中与年龄呈正相关（p = +0.72）。精子生成率最低的男性FSH水平最高，即使去除年龄影响后，FSH与每日精子生成量仍呈负相关。这些发现表明，人类睾丸对衰老的反应是可变的，并且在个体男性水平上，年龄对大多数睾丸特征的预测价值较弱。然而，年龄占间质细胞数量变化的三分之一以上，并且它解释了每日精子生成量变化的一半以上。因此，在寻找正常男性群体中睾丸结构和功能变化背后原因的研究中，年龄是迄今已确定的最大单一影响因素。
