The axonal reticulum in the neurons of the superior cervical ganglion of the rat as a direct extension of the Golgi apparatus.

Adrenergic neurons from the superior cervical ganglion of the rat have been studied with the chromaffin reaction and the zinc iodide-osmium tetroxide method. Phosphotungstic acid staining at a low pH and a combined acid phosphatase reaction and phosphotungstic acid staining have also been performed on glycolmethacrylate-embedded tissue. The results indicate that phosphotungstic acid-positive elements lacking acid phosphatase activity are present at the inner side of the Golgi apparatus. These elements give rise directly to reticular differentiations, carrying catecholamines, or to tubular extensions, representing the origin of the axonal reticulum. On these tubules, reticular differentiations can again be formed at any level. In the cell body, the differentiations are mainly found close to the neurolemma. In the axons, they are especially abundant at the axon terminals. Large granules may be associated with the reticular differentiations and small and large granules may detach from them. It is concluded that the whole catecholamine-producing and/or -storing system in sympathetic neurons can be considered as a direct extension of the Golgi apparatus, set up for local catecholamine synthesis. The relative importance of small and large granules along this system may reflect th functional status of the nerve cell.