Ultrastructural studies of the effects of reserpine on mouse abdominal sympathetic paraganglia

Male and female A/Jax mice 10–18 days of age were given one, two, or three daily subcutaneous injections of Serpasil (Reserpine USP; 2.5 mg/kg) and sacrificed 24 hours after the last injection. Abdominal extra‐adrenal tissue was processed for electron microscopy to determine the effects of this catecholamine depleting drug on the dense cored cytoplasmic granules of the parenchymal chief cells. Electron microscopic investigations of sympathetic paraganglia from treated animals revealed a marked decrease in granule opacity as compared to that seen in cells from control animals. The cells with granules reduced in opacity following reserpine treatment could be consistently distinguished from those of non‐treated animals which led us to assume that the drug depleted the amine content from its storage site in the granule without completely destroying the granule structure. These results further substantiate our earlier speculations that the granules in abdominal paraganglion chief cells of the mouse contain catecholamines.