The origin of the preganglionic parasympathetic fibres to the mandibular and sublingual salivary glands in the rat: a horseradish peroxidase study.

Horseradish peroxidase was applied to a ligation of the chorda tympani nerves running alongside the submandibular duct in order to label the preganglionic parasympathetic salivatory neurons in the brain stem. Labelled neurons were found in the ipsilateral motor trigeminal nucleus, lateral reticular formation and in the facial motor nuclei of both sides. However, the labelling of neurons in the motor nuclei of the trigeminal and facial nucleus was caused by the uptake of horseradish peroxidase by axons in the musculature surrounding the injection site which were probably damaged by the dissection procedure. The salivatory neurons were fusiform multipolar cells which were mainly located in the ipsilateral nucleus reticularis parvocellularis. No evidence for salivatory neurons in the nucleus supragenualis was found.