Premotor neurons projecting simultaneously to two orofacial motor nuclei by sending their branched axons. A study with a fluorescent retrograde double-labeling technique in the rat.

Premotor neurons innervating simultaneously two of the trigeminal motor (Vm), facial (VII) and hypoglossal nuclei (XII) by sending their branched axons were demonstrated in the lower brain stem of the rat by means of a fluorescent retrograde double-labeling method with Fast Blue (FB) and Diamidino Yellow (DY). After injections of FB and DY, respectively, into the Vm and VII, into the Vm and XII, or into the VII and XII, the majority of neuronal cell bodies labeled doubly with FB and DY were distributed in the lateral tegmental field, especially its medial part in the medulla oblongata.