Somatotopic organization of the dorsal column nuclei in the rat: transganglionic labelling with B-HRP and WGA-HRP

摘要: To analyze the patterns of cutaneous primary afferent fibers projecting to dorsal column nuclei in rat, horseradish peroxidase (HRP)-based tracers were injected intracutaneously into a number discrete regions forelimbs and hindlimbs. Three-4 days following HRP injections, rats perfused transcardially; 60 microns transverse sections cut, was reacted using tetramethyl benzidine method. Comparisons made projections injections with choleragenoid-conjugated (B-HRP) or wheat-germ agglutinin conjugated (WGA-HRP). B-HRP WGA-HRP produced similar labelling, but greater intensity labelling slightly larger projection areas. In cuneate nucleus (CN), afferents from small, delimited regions, e.g., portion skin single digit, appeared be precisely restricted rostrocaudally oriented columns, little no overlap (in mediolateral dorsoventral plane) adjacent regions. With respect rostrocaudal organization, region CN containing dense population middle, cluster, cats raccoons pars rotunda primates. Projection very consistent rat their somatotopic organization differed that suggested by electrophysiological studies: forelimb digit 1 projected near ventral border CN; those 5 dorsomedially 1; remaining digits formed crescent between 5. gracile nucleus, hindlimb more variable complex than found CN.