The fine structure of the mouse adrenal cortex and the ultrastructural changes in the zona glomerulosa with low and high sodium diets

The ultrastructure of the normal mouse adrenal cortex and the zona glomerulosa as stimulated by sodium restriction and repressed by high salt intake is reported. The mitochondria are zone specific, the endoplasmic reticulum tubular and the endothelium fenestrated. An intimate relationship between elements of reticulum, mitochondria and lipid droplets is seen in all animals. The rough reticulum is poorly developed in all but the glomerulosa of salt-restricted animals. The Golgi apparatus, associated vesicles and surface microvilli are relatively more developed in the inner cortical zones and in the glomerulosa cells of stimulated animals, whereas surface coated pits and vesicles do not vary. Lysosome-like granules are more prominant in the control reticularis and in the glomerulosa of animals on high salt intake. In stimulated glomerulosa cells, there is an early depletion of lipid droplets and a transient increase in rough reticulum followed by a progressive increase in smooth reticulum and Golgi apparatus. At three weeks, the lipid droplets are restored. In repressed glomerulosal cells, there is atrophy of the cytoplasmic organelles while lipid droplets are increased in number and osmiophilia. An accompanying feature is the appearance of cytoplasmic β-glycogen. These observations are discussed as to their relation to adrenocortical steroidogenesis and secretion.