Adrenocortical zonation of inbred wild-coloured mastomys, Praomys coucha: a new border zone in the cortex of females

Adrenal glands were examined in the inbred strain of wild-coloured mastomys (Praomys coucha), MWC. The most characteristic findings were emergence of a border zone between the zona fasciculata and z. reticularis of the cortex in females but not in males, and persistence of broad z. reticularis in males. The border zone was typically comprised of vacuolated cell layers, nodular layers and fibrous tissue. Vacuolated cells increased in number during pregnancy and partially disappeared during lactation. Growth of the nodules was greatly enhanced in both number and size during lactation. Thus, multiparae had very thick border zones composed predominantly of large nodules and, additionally, of vacuolated cells and fibrous tissue. The z. reticularis was compressed into a cord of closely packed cells by the expanded border zone in multiparous females but it continued to thicken with age in males. These changes produced completely different cortical zonation in the adrenal between sexes.