Transmission electron microscopy: a method for studying the adrenal chromaffin cells.

Transmission electron microscopy and the use of glutaraldehyde-osmium fixation allow to distinguish norepinephrine from epinephrine granules in the adrenochromaffin cells, a difficult distinction with histochemical methods if both types of granules are present in the same cell. Here we describe all the steps necessary to process the adrenochromaffin tissue for the transmission electron microscopy; this protocol is suitable for any kind of adrenal tissue, and personally we used it in mammals, reptiles, and amphibians.