Apoptosis in Thyroid Tissue from Patients with Hashimoto's Thyroiditis

Abstract

To clarify whether apoptosis of thyroid follicular epithelial cells occurs at the tissue level in autoimmune thyroiditis, 17 specimens of thyroid tissues with Hashimoto's thyroiditis were stained for fragmented DNA. Almost all nuclei of follicular epithelial cells forming atrophic thyroid follicles surrounded by mononuclear cell infiltration and fibrosis showed positive staining. With increasing distance from lymphoid cell follicles, the percentage of follicular epithelial cells with DNA fragmentation-positive nuclei decreased (30-80%). Electron microscopic study revealed the existence of epithelial cells with shrunk and condensed nuclei. The frequency of those cells in different areas was almost 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.

Key Words:

• Apoptosis
• thyrocyte
• Hashimoto's thyroiditis