GROWTH AND HORMONE CHARACTERISTICS OF PUBERTAL DEVELOPMENT IN THE HAMADRYAS BABOON

The semi-longitudinal collection of growth measurements in male and fe male hamadryas baboons has enabled documentation of the timing of pube rty and the development of sexually dimorphic growth patterns in body weight, crown-rump length (CRL), limb lengths, and muscle mass. In add ition, another sexually dimorphic characteristic appears to be the pre sence of a pubertal growth spurt in body weight, and possibly CRL, in male but not female baboons. Serum testosterone levels rose during mal e development; however, there was a progressive decrease in dehydroepi androsterone sulfate levels indicating the absence of adrenarche. Insu lin-like growth factor-I (IGF-I) and its major binding protein, IGFBP- 3, both rose during pubertal development; however, a simultaneous rise in the IGF-I:IGFBP-3 molar ratio suggests other factors may enhance t he bioactivity of IGF-I during puberty. A distinct rise in serum osteo calcin levels was also associated with puberty in male baboons. These growth and hormonal changes during puberty in the hamadryas baboon ind icate that this species provides a close primate model for human puber ty.