The distribution of N-acetylgalactosamine in the cochlear nucleus of the gerbil revealed by lectin binding with soybean agglutinin

Abstract

A horseradish peroxidase conjugated lectin from Glycine max (soy bean agglutinin; SBA) was used to characterise the distribution of N-acetylgalactosamine in the cochlear nucleus of the mongolian gerbil. SBA bound differentially to a variety of structures within the cochlear nucleus. Specific SBA labelling was associated with large non-granule neurones of variable size and shape throughout the cochlear nucleus. Compared to adjacent Nissl-stained sections 80% of the non-granule cells in the dorsal cochlear nucleus (DCN) and more than 90% of the non-granule cells in the ventral cochlear nucleus (VCN) bound SBA. The variation in location, size and shape as well as the high percentage of the labelled neurones suggest that cells of several, if not all, non-granule cell types, which have been described for the cochlear nucleus according to the usual Nissl schemes, are SBA positive. Granule cells did not bind SBA because all SBA-labelled cells had diameters above 10 μm. Diffuse labelling, not systematically associated with cells or fibres, was high in the molecular and fusiform cell layers of the DCN and that part of the granule cell area located close to the surface of the VCN. Darkly labelled granules (up to 2 μm diameter) were prominent in the area of the VIIIth nerve root. After long SBA incubations, they were also present in VCN and to a lesser degree in DCN. The results are discussed with respect to findings in other brain areas and the possible co-localisation of gamma aminobutyric acid (GABA), parvalbumin and N-acetylgalactosamine.