An ultrastructural stereologic study of aldosterone secreting adrenal adenomas and of adjacent zona glomerulosa

Abstract

The ultrastructure of four aldosterone secretine adenomas and of the adiacent zona glomerzosa has been described by "the use of stereological techniques. Adenomatous cells (about 2800 pm' in volume) invariably displayed a striking abundance of lipid droplets. which occupied about 30% of the cytoplasm. Mitochondria prevalently contained tubulo-lamellar or lamellar cristae, hut some cells exhibited organelles with vesicular cristae. Smooth endoplasmic reticulurn (SER) was not very abundant. Small lipofuscin-pigment granules were frequently seen and in a few cells they were exceedingly numerous. Zona glomerulosa cells were smaller (about 950 pm3 in \~olume) and possessed mitochondria with typical tubulo-lamellar cristae, a plentiful SER and few lipid droplets. They showed the ultrastructural features of elements actively engaged in steroid synthesis. The possible origin of aldosteronoma cells from the zona glomerulosa is discussed.