The effect of subdermal testosterone filled polydimethylsiloxane implants on spermatogenesis in rhesus monkeys (Macaca mulata)

Abstract Testicular and accessory sex organ function was examined in 36 adult male rhesus monkeys after receiving varying amounts of testosterone via subdermal polydimethylsiloxane implants. Testicular sperm production declined to one-fifth of control levels when testosterone was administered at the rate of 34 μg/lb body weight. Despite marked reduction in sperm production, serum LH concentrations were unchanged while plasma testosterone concentrations and accessory sex organ weights increased significantly in comparison to control monkeys. These results suggest that testosterone failed to completely suppress pituitary gonadotropin secretion and subsequently spermatogenesis in rhesus males as it did in rabbits.