Normal development of the zona reticularis with age

Illustration of the normal development of the zona reticularis with age. The zona reticularis of the adrenal cortex is normally established as a distinct, continuous zone after 3 years of age, is well established by 8 to 9 years of age, and continues to grow and develop until early adulthood. The characteristic changes in the level of expression of differentially expressed key genes in each of the adrenocortical zones is depicted schematically, along with the major secretory product(s) of each zone. Larger and bold fonts indicate that relatively large quantities of the hormone are produced.