Comparative analysis of NADPH-diaphorase positive neurons in the rat, rabbit and pheasant thoracic spinal cord. A histochemical study

The distribution of NADPH-diaphorase (NADPH-d) activity was investigated an d compared in the rat, rabbit and pheasant thoracic spinal cord. The invest igation of all spinal cord regions (laminae) in three experimental species revealed marked differences in the distribution of NADPH-d activity. Cross sectional analysis of the spinal cord of the rat, rabbit and pheasant confirmed differences in the shape of the gray matter in all examined spec ies. More detailed investigation of Rexed's laminas showed similar distribu tion of NADPH-d activity in the spinal cord of the rat and rabbit, which we re different when compared with the spinal cord of the pheasant. Ventral horn of the rat and rabbit showed no labelling whereas in pheasant this area possessed a number of scattered, intensively stained neurons. In the location of autonomic preganglionic neurons, differences were found as well. In the rat there was seen a number of densely packed, clearly dark bl ue coloured neurons. Similarly, these neurons were present in the rabbit sp inal cord but they were less numerous. No staining was found in this region of pheasant. Pericentral area (lamina X) and intermediate zone (lamina VII ) revealed the presence of NADPH-d positive neurons in all examined species although they differed in number and shape of their bodies. The dorsal hor n showed the presence of NADPH-d staining in all three animals but its dist ribution was different in medio - lateral direction. It can be suggested that observed differencies in the presence and distribu tion of NADPH-d activity across the examined species may reflect different fylogenetic development.