Genetic association between agouti locus and adrenal X zone morphology in SM/J mice.

We provide evidence for a genetic link between the adrenocortical X zone and the agouti (a) locus on chromosome 2 in the segregating inbred mouse strain SM/J. This strain has been established and maintained while keeping heterozygosity (Aw/a) at the a locus and is, therefore, of advantage in assessing the effects of these alleles upon physiological phenomena. In Aw/a (white-bellied agouti) or a/a (black) virgins, X zones were composed exclusively of nonvacuolated cells, while they contained vacuolated cells only in Aw/Aw. This suggested that the a locus might control the X zone morphology on the SM/J genetic background and that the a (nonagouti) allele is dominant in vacuolation of cells in this zone. The a locus might have a novel function in the control of the adrenocortical X zone cell turnover in addition to the well-known function controlling the coat color.