SPONGIFORM DEGENERATION OF THE GERBIL COCHLEAR NUCLEUS - AN ULTRASTRUCTURAL AND IMMUNOHISTOCHEMICAL EVALUATION

Observations from ultrastructural and immunohistochemical studies sugg est that spongiform lesions in the gerbil cochlear nucleus are derived principally from dendrites. Almost orle-fifth of the lesion profiles examined ultrastructurally exhibited synaptic contacts with axon termi nals. In addition, approximately 80% of lesions are immunopositive for the dendrite-specific microtubule associated protein, MAP2. Ultrastru ctural studies showed a small percentage (8%) of lesions were derived from myelinated axons, although none were immunohistochemically labell ed with antibodies to the tau protein. Staining with the astrocyte-spe cific markers GFAP, S-100 and vimentin yielded equivocal results, but did not support a major role for astrocytes in lesion formation. The h istological profile matches that seen in some other well characterized types of spongiform degeneration.