THE DISTRIBUTION OF N-ACETYLGALACTOSAMINE IN THE COCHLEAR NUCLEUS OF THE GERBIL REVEALED BY LECTIN-BINDING WITH SOYBEAN AGGLUTININ

A horseradish peroxidase conjugated lectin from Glycine max (soy bean agglutinin; SBA) was used to characterise the distribution of N-acetyl galactosamine in the cochlear nucleus of the mongolian gerbil. SBA bou nd differentially to a variety of structures within the cochlear nucle us. Specific SBA labelling was associated with large non-granule neuro nes of variable size and shape throughout the cochlear nucleus. Compar ed 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 labe lled neurones suggest that cells of several, if not all, non-granule c ell types, which have been described for the cochlear nucleus accordin g to the usual Nissl schemes, are SBA positive. Granule cells did not bind SBA because all SBA-labelled cells had diameters above 10 mu m. D iffuse 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 mu m diameter) were prominent in t he area of the VIIIth nerve root. After long SBA incubations, they wer e also present in VCN and to a lesser degree in DCN. The results are d iscussed with respect to findings in other brain areas and the possibl e co-localisation of gamma aminobutyric acid (GABA), parvalbumin and N -acetylgalactosamine.