Fibers of trigeminal mesencephalic neurons in the maxillary nerve of the rat.

Indirect Wallerian degeneration after sectioning the infraorbital nerve, and retrograde axonal transport following injection of horseradish peroxidase (HRP) into the maxillary nerve were studied in rats. These experiments showed the existence of primary trigeminal neurons in the pars caudalis of the ipsilateral trigeminal mesencephalic nucleus and in the supratrigeminal nucleus of Lorente de Nó. Such neurons were interpreted as being responsible for the sensitive innervation of the periodontal membrane.