Representation of tooth pulp in the mesencephalic trigeminal nucleus and the trigeminal ganglion in the cat, as revealed by retrogradely transported horseradish peroxidase.

Horseradish peroxidase (HRP) injection into the tooth pulp of the left lower canine in 4 adult cats resulted in labeling a maximal number of nerve cell bodies of 45 and 149 ipsilaterally in the mesencephalic trigeminal nucleus (MTN) and trigeminal ganglion (TG), respectively. In a cat subjected to HRP application to the same canine and subsequent 3 posterior teeth, the respective numbers of labeled neurons in MTN and TG were increased to 92 and 933, respectively.