ADRENOCORTICAL ZONATION IN CHAMOIS-COLORED MASTOMYS, PRAOMYS COUCHA

Body and adrenal weights, and histology of the adrenal cortex were exa mined in the chamois-coloured mastomys (Praomys coucha) at inbred gene rations 3 to 10. Body and adrenal weights were consistently larger in males than in females, although the adrenal to body weight ratios tend ed to be lower before 50 days of age and were clearly higher after. Di stinct sex differences were found in the adrenal carter. The whole cor tex and the zona reticularis were thicker in males and the zona reticu laris became thicker in males, but thinner in females with age. The bo rder zone characteristics of females of the wild-coloured mastomys str ain, was not formed in the chamois-coloured strain. This was a very un ique, interesting strain difference. Comparative studies of both strai ns may contribute to elucidation of the mechanism of border zone forma tion in the mastomys adrenal cortex.