A study of pre- and postganglionic fibres in the intestinal nerve (Remark's nerve) of the chicken.

The mean peak CV's of two electrophysiologically defined groups of fibres in the intestinal nerve of the chicken have been determined. One group of fibres is constituted by the processes of enteric cholinergic neurones which project along the side branches of the intestinal nerve and synapse within the nerve trunk. These preganglionic fibres have a mean peak CV (at 40 degrees C) of 0.31 m x s-1. The other group is made up of fibres of postganglionic neurones which project orally along the nerve trunk. The results suggest that some postganglionic neurones project only as far as the next ganglion whilst others project beyond the next two ganglia for distances greater than 5 mm. The postganglionic fibres have a mean peak CV (at 40 degrees C) of 0.71 m X s-1. These figures demonstrate that both pre- and postganglionic fibres are unmyelinated. The temperature coefficient (Q10) for the CV of unmyelinated fibres in the intestinal nerve was 1.57.