PROJECTION FROM TRIGEMINAL NUCLEI TO NEURONS OF THE MESENCEPHALIC TRIGEMINAL NUCLEUS IN RAT

The mesencephalic trigeminal nucleus contains cell bodies of primary s omatic sensory neurons that innervate the head region. The neurons res emble dorsal root ganglion cells but a striking difference is the pres ence of synaptic boutons in the nucleus. The present report demonstrat es with anterograde tracers, the existence of a direct trigeminal proj ection from secondary sensory neurons of the principal and spinal nucl ei to the mesencephalic nucleus. Our observations strongly suggest tha t synaptic contact may be established on the cell bodies as well as on the neurites of the mesencephalic neurons. These pathways could play a modulatory role in the processing of sensory afferent information an d in the control of orofacial and/or oculomotor functions. (C) 1997 El sevier Science Ireland Ltd.