IMMUNOELECTRON MICROSCOPIC LOCALIZATION OF VIMENTIN IN SUSTENTACULAR CELLS OF THE CAROTID-BODY AND THE ADRENAL-MEDULLA OF GUINEA-PIGS

The sustentacular cells of the carotid body and the adrenal medulla of guinea pigs were studied by light and electron microscopic immunohist ochemistry and compared with the Schwann or satellite cells of the per ipheral nervous system. In the peripheral nervous system, neurons were immunoreactive for protein gene product (PGP) 9.5, whereas Schwann ce lls or satellite cells were immunoreactive for S-100 protein and vimen tin. Vimentin immunoreactivity was detected on the intermediate filame nts of the Schwann cells by postembedding immunogold labeling. In the carotid body and the adrenal medulla, glomus cells or chromaffin ails were closely enveloped by the sustentacular ails, which protruded long cytoplasmic processes and had some axons embedded in them, as in Schw ann cells. The glomus cells or chromaffin cells expressed immunoreacti vity for PGP 9.5, whereas the sustentacular cells expressed immunoreac tivity for S-100 protein and vimentin. The sustentacular cells were ch aracterized by the presence of abundant intermediate filaments on whic h immunogold particles for vimentin were densely located. From these r esults, it is concluded that the sustentacular cells closely resemble glial cells of the peripheral nervous system in immunohistochemical, u ltrastructural, and also functional properties, and may belong to the glial lineage, originating from the neural crest.