Corticotrigeminal motor pathway in the rat--II. Anterio- and retrograde HRP labeling

1. Horseradish peroxidase (HRP) injection into the rat cortical jaw motor area (JMA) disclosed direct projection fibers in and around the motor trigeminal nucleus (MTN), primarily contralaterally. 2. Descending axons were found in the ventromedial half of the cerebral peduncle and MTN-projecting axons were concentrated near the descending facial nerve root. 3. HRP injection into the peduncle could label 1257 cells in the JMA, 128 cells in the taste area and 1409 cells in the neck-forelimb motor area ipsilaterally. 4. Some MTN-terminated axons could be traced from the peduncle in serial sections.