UC San Diego

The medullary connections of the subdivisions of the rostral and caudal nucleus of the solitary tract (NST) of the medulla were elucidated in the mouse model. Tract tracing experiments involving injections of Cholera toxin subunit B delivered by iontophoresis aimed at subdivisions of the NST, the area postrema, or the reticular formation investigated the hypothesis that the subnuclei within the NST have differential connections. Subsequent visualization of transported anterograde labeling of axonal endings and retrograde labeling of cell bodies throughout the medulla was accomplished with immunohistochemical techniques. Labeled cells and endings were plotted in relation to an atlas of cell groupings revealed with a routine histological counterstain. The results show intra-NST connections and differential connections depending on the sites injected