Submicroscopic Changes of the Nerve Endings in the Adrenal Medulla after Stimulation of the Splanchnic Nerve

Abstract

The nerve endings of the adrenal medulla of the rabbit were studied under the electron microscope in the normal condition and after prolonged electrical stimulation of the splanchnic nerve. With a stimulus of 100 pulses/second for 10 minutes, there is an increase in the number of synaptic vesicles in the nerve ending. The mean number is 82.6 vesicles/sq. micron in the normal and 132.7/sq micron in the stimulated glands. With a stimulus of 400 pulses/second for 10 minutes, there is a considerable depletion of synaptic vesicles and other changes occur in the nerve endings. The mean number of vesicles is 29.2/square micron. These results are interpreted as indicative of an increased activity of the ending in 1 case, and as a diminished activity and fatigue of the synaptic junction in the other.