The location of cells of origin of the fibers in the ventral and the lateral funiculus of the cat's lumbo-sacral cord

Abstract

Propriospinal fibers in different portions of ventral and lateral funiculi of cat's lumbo-sacral cord are distributed preferentially to different motoneuronal cell groups 28. The present study tried to determine the cells of origin of these fibers by means of the retrograde degeneration technique. In kittens either the spinal cord was hemisected at or above L1 or parts of ventral and lateral funiculi were transected between L4 and S1. The distribution of chromatolytic cells indicates that ascending pathways are derived mainly from cells in lamina IV and in lamina VIII as well as from large elements in the lateral part of the intermediate zone from L3 to L6 (area of spinal border cells). The results further indicate that short propriospinal fibers are derived mainly from cells in the intermediate zone. The bulk of these fibers in the ventral funiculus and ventral part of the lateral funiculus are derived from the medial and central parts of ipsilateral lamina VII. However, some fibers in the medial part of the ventral funiculus are derived also from contralateral lamina VIII while the fibers in the dorsal part of the lateral funiculus are derived mainly from the lateral parts of ipsilateral laminae VII, VI and V.