This project is concerned with the synaptic connections of the sensory root of the trigeminal nerve and the morphology of the neurons which comprise the main sensory and spinal trigeminal nuclei. These studies employ electron microscopy, the Golgi method and the use of intraneuronal markers such as horseradish peroxidase. The objects of these studies are to delineate trigeminal pain-temperature pathways and to broaden our understanding of oral-facial sensation.