Evolution of reproductive strategies of the human and great apes

为了弄清楚人类和类人猿的生殖策略模式，我们试图估计这些物种的精子产量，并比较睾丸的组织学方面。我们通过尸检或活检获得了人类（N=7）、大猩猩（10）、黑猩猩（11）、猩猩（7）的睾丸标本，并在光学显微镜下进行了观察。结果表明，在人类（6/7）、黑猩猩（10/11）、猩猩（7/7）的大多数样本中检测到精子发生，而在大猩猩的少数个体中检测到精子发生（4/10）。然而，类人猿的值与人类的值没有显著差异。人的间质组织疏松而稀少。间质细胞在大猩猩中相当密集，在黑猩猩中相当少，在其他两个物种中居中。所有物种的曲细精管直径和曲细精管在间质组织中的比例均无显著差异。与黑猩猩和猩猩相比，人类的曲细精管（TLT）的平均估计总长度明显较短。人的精子和成熟精子细胞数低于黑猩猩。这些物种的平均精子发生指数（SI=TLT × CN）存在显著差异，即人类的精子发生指数小于黑猩猩和猩猩，而大于大猩猩。因此，我们估计黑猩猩、猩猩和大猩猩通常分别产生人类的60倍、4倍和1/4倍的精子。

To make clear the pattern of reproductive strategies in the human and great apes, we attempted to estimate sperm production in these species and to compare histological aspects of testes. We obtained testicular preparations of the human (N=7), gorilla (10), chimpanzee (11), orangutan (7) by autopsy or biopsy, and observed them using light microscopes. As the results, spermatogenesis was detected in most samples in humans (6/7), chimpanzees (10/11), orangutans (7/7), but in few individuals in gorillas (4/10). However, the values in great apes were not significantly different from that in the human. The interstitial tissue of the human was loose and scarce. Leydig cells were quite dense in gorillas and quite few in chimpanzees, and intermediate in the other two species. There were not significant differences in diameters of seminiferous tubules nor proportions of seminiferous tubules in the interstitial tissue in all species. The mean estimated total length of seminiferous tubules (TLT) in humans was significantly short, compared with that in chimpanzees and orangutans. The sperm and mature spermatid count per tubule (CN) of humans was less than chimpanzees. The mean spermatogenetic index, calculated as SI=TLT × CN in these species was significantly different from each other, namely that in humans was less than chimpanzees and orangutans, but more than gorillas. Thus, we estimated that a chimpanzee, orangutan, gorilla usually produce 60 times, 4 times and 1/4 time sperm than humans, respectively.