Comparison of adrenocortical zonation in C57BL/6J and DDD mice.

Adrenal weights and adrenocortical zonation were compared in two inbred mouse strains, C57BL/6J and DDD, which are different in both origin and genetic background. Clear strain and sex differences were observed in the adrenal weight and the morphology of the zona fasciculata, z. reticularis and X zone. DDD adrenals were larger than C57BL/6J ones regardless of sex. The z. fasciculata was thicker in female than male DDD mice. The z. reticularis of DDD males developed nodules at 70 days of age, followed by an increase in size with age, while that of C57BL/6J males did not. Parous females experiencing pregnancy, gestation and lactation also developed similar nodules, but virgins did not. The X zone degeneration occurred earlier in males than in females. This zone disappeared before 5 weeks of age in males but gradually decreased in thickness with age in DDD virgins. The female X zone was thicker and degenerated with vacuolation in DDD, while it was thinner and degenerated without vacuolation in C57BL/6J. Such clear strain differences in the inner cortices, z. reticularis and X zone, suggested that their morphology might be regulated primarily by genetics and modified by endocrinology.