Light and electron microscopic changes of hyperplastic adrenal cortices from two patients with Cushing's syndrome were reported. The ultrastructural findings were characterized by the increase of lipid inclusions, a large number of intochondria, vacuoles in mitochondria and also the increase of sER in some cells. Observations of the intramitochondrial vasuoles support the view that steriod sythesis may take place within the mitochondria, but their biological significance still remains to be elucidated
