This project is designed to evaluate a possible role for the adrenal in the control of reproductive inhibition in the prairie deermouse (Peromyscus maniculatus). This species has been shown to control numerical population growth via a natural suppression of reproductive maturation in young born into dense populations. The basic mechanism for this appears to involve a failure of at least 90% of these young to pass through puberty. This inhibition is completely reversible if the inhibited animals are removed from the population context. We have previously characterized some of the reproductive endocrine physiology of deermice in the normal and inhibited state and have shown that the adrenals have different cellular morphology. We propose here to further evaluate the possible association of the adrenal with reproductive inhibition. In order to accomplish this objective we shall first characterize the normal deermouse pubertal transition in terms of adrenal and gonad cellular development at both the light and electron microscopic level. We shall also measure by RIA the serum levels of corticosterone, dehydroepiandrosterone and its sulfate ester, testosterone and estrogen. Finally, the adrenal cell activity of the P450c17 enzyme pathway will also be assessed with molecular probes. This study should reveal the nature and degree of the relationship between adrenal development and gonad maturation in the normal pubertal transition of deermice. Any significant differences in this process, as they may pertain to the development of the adrenal and gonad in the reproductively inhibited animal, will be carefully evaluated with the intention of addressing the possibility that control points for the induction and maintenance of the inhibition are based within the adrenal.