Autoradiographic studies of the projections of the midbrain reticular formation: descending projections of nucleus cuneiformis.

The descending projections of nucleus cuneiformis in the cat were traced by autoradiography in the transverse and sagittal planes following stereotaxically placed injections of 3H-leucine. Many descending axons are organized into distinct fiber systems, of which the largest and most well-defined crosses directly in the midbrain and descends through the ventromedial tegmentum of the brain stem. This fiber system first terminates profusely in n. reticularis tegmenti pontis and then proceeds through the rhombencephalic tegmentum emitting transversely oriented branches to n. reticularis pontis caudalis and gigantocellularis, the raphe magnus and the facial nucleus...