FACIAL-NERVE PARASYMPATHETIC PREGANGLIONIC AFFERENTS TO THE ACCESSORYOTIC GANGLIA BY WAY OF THE CHORDA TYMPANI NERVE IN THE CAT

The distribution of accessory otic ganglia and connections between the ganglia and the chorda tympani nerve were investigated in the cat in order to determine the parasympathetic preganglionic facial nerve affe rents to the otic ganglia using whole mount acetylthiocholinesterase ( WATChE) histochemistry. The otic ganglia consist of a sigle main promi nent ganglion and many small accessory ganglia lying on a plexus aroun d the origins of the branches of the mandibular nerve and near the jun ction of the chorda tympani nerve and lingual nerve. In cell analysis of Nissl-stained preparations, the neurons composing the accessory oti c ganglia were morphologically similar to the main otic ganglion neuro ns. Connecting branches from the chorda tympani nerve to the periphera lly located acccessory otic ganglia were found and they were not stain ed by WATChE histochemistry. WATChE-positive connecting branches from the ganglia to the inferior alveolar, lingual, and mylohyoid nerves we re also found in the same preparations. The WATChE histochemistry on v arious autonomic nervous tissues revealed that autonomic postganglioni c nerve fibers are selectively stained darkly and that preganglionic f ibers remain unstained. Therefore, it is considered that the WATChE-ne gative connections from the chordra tympani nerve consist chiefly of a utonomic preganglionic fibers, whereas the WATChE-positive connections to the branches of the mandibular nerve are mainly postganglionic fib ers. This suggests that some of the facial nerve parasympathetic prega nglionic fibers in the chorda tympani nerve are mediated in the access ory otic ganglia and then join the branches of the mandibular nerve to supply the target mandibular tissues.