A stereological study of adrenocortical cells in spontaneously hypertensive rats (shr).

The ultrastructure of SHR (Spontaneously Hypertensive Rats) fasciculata cells was compared descriptively and quantitatively with that of nonstimulated fasciculata cells of Wistar rats using sterological methods. The volume and surface densities are expressed per cm3 of cytoplasm. The smooth endoplasmic reticulum in the SHR was significantly increased compared to the control animals (surface density : 28%, volume density: 35%). Mitochondria volume remained unchanged although the inner mitochondrial membranes were significantly reduced (37%). An attempt was made to draw up a relation between sterological and biochemical data of steroid synthesis within the fasciculata cell. A genetically determined enzymatic defect in the early steps of the transformation of cholesterol to pregnenolone may exist at the level of the inner mitochondrial membrane. Whether this altered steroid metabolism is important to the etiology of hypertension in the SHR requires further investigation.