Soybean agglutinin binds to a subpopulation of primary sensory neurones in the cat.

The binding of the plant lectin soybean agglutinin (SBA) to primary sensory neurones has been investigated in the rat. SBA binding was found in Lissauer's tract and in laminae I and IIo of the dorsal horn at cervical, thoracic and lumbar levels. Morphometric analysis of the S1 dorsal root ganglia revealed that SBA binding was associated with the small diameter cell population, considered to be the cell bodies of unmyelinated afferent fibres (C-fibres). These findings suggest that SBA may be a useful ultrastructural marker for C-fibre terminals.