The fine structure of the zona glomerulosa and the zona fasciculata of the adrenal cortex of the opossum

Abstract

Abstract The normal fine structure of the zona glomerulosa and the zona fasciculata of the opossum is described, with emphasis on the structure of the smooth surfaced endoplasmic reticulum (SER) and mitochondria. The cells of the zona glomerulosa are characterized by the presence of numerous rod‐shaped mitochondria with shelf‐like cristae, small amounts of tubular SER and moderate amounts of rough surfaced endoplasmic reticulum. The cells of the zona fasciculata possess large quantities of SER, spherical mitochondria with tubular cristae and a few profiles of rough surfaced reticulum. A Golgi apparatus is present in cells of both zones as are coated vesicles, coated invaginations of the plasmalemma, lysosomes and lipid droplets. It is concluded that the tubular SER seen in electron micrographs corresponds closely to the form of this membrane system found in the living cell. The functional significance of the associations observed among lipid droplets, mitochondria and SER are discussed.