Male rats were exposed to 4,340 m altitude for 4 days. At this time histological alteration in the testes were observed. There were tubules with pyknotic primary spermatocytes and spermatids, necrosis of numerous cells, and sloughing of primary spermatocytes. The damaged areas were limited by normal tissue. Serum testosterone increased significantly after 4 days of exposure. Administration of an anti-serotoninergic compound, cyproheptadine (10 mg/kg body weight), prevented the high altitude-induced changes in both spermatogenesis and serum testosterone. These observations suggest that serotonin is involved in the testicular changes that occurred when rats are acutely exposed to high altitude.

Stature and weight of native children, adolescents, and adults at Huancayo , Peru (3,280 meters), were measured in 1977, 1978, and 1982 and compared with mean statures and weights reported in previous studies. The data indicate that in Huancayo there has been a secular increment in child stature, sitting height, and weight from 1937 to 1978-1982. The observed changes in stature are related to a proportionally greater increment in leg length relative to trunk length. It is concluded that the observed secular increase in body size reflects changes in the standard of living and a greater influx of nonnative populations, which are usually characterized by greater stature than natives.