American Journal of Primatology 2630WJ14 (1992) BRIEF REPORT Endocrine and Developmental Correlates of Unilateral Cryptorchidism in a Wild Baboon

A wild, group-living 8.5-year-old adult baboon was found to have only a single palpable testicle, the only case of cryptorchidism found among more than 200 males that we have examined. This young adult had an unusu-ally small body size for his age, one that was comparable to that of imma-ture males two years younger, and during maturation his body mass was increasingly small for his age. As a young adult, he also had very low testosterone concentrations, which, in combination with his small size, history of impaired growth, and the absence of any obvious scars around the scrotum, suggest that this is a case of spontaneous unilateral cryp-torchidism of unknown cause rather than one of monorchidism arising from injury. Despite striking differences in his growth, adult body size, and testosterone levels, the male's cryptorchidism seemed to have rela-tively little effect on his social and sexual maturation in his natal group. Nonetheless, it may be related to his inability to gain entry into another group after dispersal. Key words: baboons, social maturation, physical maturation, testosteron