[Horseradish peroxidase-labeled cells as sources of the spinoreticular and spinothalamic systems of the brain].

The cells of spinoreticular and spinothalamic fibrous systems of the cat brain were studied by the method of axone transmission of horse-radish peroxidase (HP). A dense accumulation of HP-labeled neurons establishing direct relations with the reticular formation and thalamus was seen in the upper segments of the spinal cord. In the lower segments these zones were confined to the medial part of the ventral horn and the intermediate zone of the gray matter. The neurons established direct connections with contralateral nuclei of the reticular formation as well as with the thalamus ipsi- and contralateral nuclei. Possible pathways of transmitting somatic and pain sensitivity are discussed.