Excitation of Ganglion Cells in the Inferior Mesenteric Ganglion by Collaterals

Abstract

WHEN the hypogastric nerve is stimulated with a current which is subthreshold for the postganglionic C fibres but sufficiently strong to stimulate the delta and B fibres, a number of cells in the inferior mesenteric ganglion are excited, and an impulse coming from the ganglion can be recorded in the hypogastric nerve. An impulse is also recorded on stimulation of the contralateral hypogastric nerve¹ (see diagram). If in a curarized preparation a conditioning tetanus is given preganglionically, a test shock to the postganglionic hypogastric nerve afterwards excites a larger number of ganglion cells. Now post-tetanic potentiation, also in the curarized ganglion, is exclusively localized to the stimulated fibres. Therefore these ganglion cells must have been excited through collaterals. This reflex persisted, when the afferent fibres, after bilateral excision of the spinal ganglions, Th 11—L VI, had been denervated. It was absent after sections and degeneration of the ventral roots of the same segments. Consequently, these collaterals are given off from efferent fibres which traverse the ganglion, and have their trophic centre in the spinal cord.