Immunohistochemistry and effect of vinblastine on intracisternal microtubules of the canine neurons.

The immuno-histochemical and drug-binding properties of intracisternal microtubules (IMs) in the RER of canine neurons were studied with antitubulin IgG and vinblastine. Specific fluorescence against antitubulin IgG was not detected in the RER in which the IMs were aggregated but was observed in the cytoplasm outside the RER. Injection of vinblastine into the sympathetic ganglion did not change the size, shape or arrangement of IMs in the RER, although typical honeycomb crystals were formed near IM-containing RER. These findings show that the IM does not possess antigenicity to antitubulin IgG and has no vinblastine-binding site. Thus it is suggested that the IM may be a defective or modified microtubule.