DESCENDING TRACTS OF THE LATERAL COLUMNS OF THE RAT SPINAL-CORD - STUDY USING THE HORSERADISH-PEROXIDASE AND SILVER IMPREGNATION TECHNIQUES

Abstract

The location of cells of origin and projection areas of descending spinal cord lateral column fiber tracts was examined in rats. Unilateral anterolateral (AL) or dorsolateral (DL) column transection at C(cervical)2 or T(thoracic)10 with subsequent horseradish peroxidase (HRP) application allowed the identification of the cells of origin (HRP technique) or projection areas (Ag impregnation technique) of transected fibers. Cells of origin of fibers coursing through both the AL and DL columns were located in nucleus reticularis ventralis and gigantocellularis, nucleus subcoeruleus, raphe magnus and the paraventricular hypothalamic nucleus. Fiber tracts coursing through the AL but not DL columns had cells of origin in the lateral vestibular nucleus and nucleus reticularis pontis oralis. Fiber tracts coursing through the DL but not AL columns had cells of origin in the red nucleus and area A7. Cells of origin of lateral column fibers observed following C2 but not T10 HRP application were located in the descending vestibular nucleus, superior colliculus, raphe pallidus and the interstitial nucleus of Cajal. Following either an AL or DL column transection intense degeneration was observed caudally in laminae V, VI and VII; following a DL column transection degeneration was also observed in laminae II, III, IV and VIII.