Visualization of intrarenal catecholamine-containing elements: fluorescence histochemistry and electron microscopy.

Fluorescence histochemistry and electron microscopy were used to study catecholamine-containing elements in rat and cat kidneys. There were fluorescent nerve plexuses associated with the arterial system of the renal cortex from which nerves extended into the medulla forming dense networks in the vascular bundles of the outer part of the medulla. Also, there were small cells found singly and in clusters which emitted the blue fluorescence characteristic of catecholamine-containing cells. These cells were associated with the periarterial nerve plexuses and were frequently encountered in the cat medullary vascular bundles. Electron microscopy of the cat renal medulla revealed processes with the structure of typical adrenergic terminals and other processes that resemble small intensely fluorescent (SIF) cell processes.