Reproductive endocrinology of female chimpanzees: a suitable model of humans.

Similarities between reproductive processes in humans and chimpanzees have led to speculation that the chimpanzee might be an excellent reproductive-endocrine model of humans. Data comparing patterns and concentrations of serum gonadotropins, prolactin, and sex steroids in female humans, chimpanzees, and rhesus monkeys sustain this concept. The striking evidence that levels of estrone, estradiol, estriol, progesterone, and chorionic gonadotropin are similar during human and chimpanzee pregnancy support the contention that chimpanzees, like humans but unlike rhesus monkeys, have a definitive fetoplacental unit. Likewise, during normal menstrual cycles serum patterns of LH, FSH, progesterone, and estradiol are similar in women and chimpanzees, but differ in rhesus monkeys. Thus by using the chimpanzee it may be possible to accurately assess the safety for human use of compounds that might affect reproductive-endocrine processes without direct exposure to humans.