Phaeochromocytoma, Electron microscopic study on catecholamine storage.

The biochemical and electron-microscopical findings of eight cases of phaeochromocytoma and the ultrastructure of two cases of human adrenal medulla are presented here as regards catecholamine storage. Due to the rarity of phaeochromocytoma, other ultrastructural features are also described. The morphological characteristics of catecholamine-containing granules are considered on the basis of our investigations and results of other authors. These characteristics are discussed from the point of view of their value in the morphological differentiating of granules storing norepinephrine and those storing epinephrine.