Abstract
This chapter reviews small intensely fluorescent (SIF) cells in vivo and in vitro. In earlier experiments, fluorescence induced by formaldehyde was shown to demonstrate noradrenaline-containing chromaffin cells in the adrenal medulla. With an improved modification of this method, catecholamines were demonstrated not only in the cytoplasm of sympathetic nerve cells, but also in small cells in sympathetic ganglia which exhibited an extremely bright fluorescence. These cells are now commonly called “small intensely fluorescent” cells or SIF cells. Against expectations, these cells were observed to be non-chromaffin. The presence of SIF cells in various sympathetic ganglia of several species has been firmly established by fluorescence microscopy. Clusters of SIF cells are especially common near blood vessels, a position suggesting either endocrine function or regulation of the SIF cells by hormonal factors via the blood stream. On the other hand, SIF cells and their processes have been found on sympathetic nerve cell bodies and fibers in a manner which suggests that the SIF cells may influence the nervous transmission by catecholamine liberation.
Published Version
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