IMMUNOHISTOCHEMICAL DEMONSTRATION OF THYROID HORMONE IN PARAFFIN EMBEDDED HUMAN THYROID TISSUES

The immunoperoxidase technique was shown to be applicable to localization of thyroxine (T4) and triiodothyronine (T3) in 10% formalin fixed paraffin sections of human thyroid tissues including tumors. T4 was demonstrated in the colloid substance and on the luminal surface of the follicular epithelia, and less frequently in the cytoplasm of the non-neoplastic epithelia. On the contrary, cytoplasmic staining of T4 was remarkable in some thyroid tumors. The T3 localization was observed rather in the cytoplasm of the epithelial cells than in the colloid substance. It is noteworthy that most of the thyroid neoplasms which were clinically diagnosed as non-functioning showed more or less positive staining for either T4 or T3.