APOPTOSIS IN THYROID-TISSUE FROM PATIENTS WITH HASHIMOTOS-THYROIDITIS

To clarify whether apoptosis of thyroid follicular epithelial cells oc curs at the tissue level in autoimmune thyroiditis, 17 specimens of th yroid tissues with Hashimoto's thyroiditis were stained for fragmented DNA. Almost all nuclei of follicular epithelial cells forming atrophi c thyroid follicles surrounded by mononuclear cell infiltration and fi brosis showed positive staining. With increasing distance from lymphoi d cell follicles, the percentage of follicular epithelial cells with D NA fragmentation-positive nuclei decreased (30-80%). Electron microsco pic study revealed the existence of epithelial cells with shrunk and c ondensed nuclei. The Frequency of those cells in different areas was a lmost compatible with that of cells with fragmentation-positive nuclei . These findings suggest that apoptosis plays an important role in the thyroid tissue injury in autoimmune thyroiditis.