Identification of C-Cells in Normal and Goitrous Rat Thyroid Tissues Using Antiserum to Rat Thyrocalcitonin and the Immunoperoxidase Bridge Technique

Abstract

Application of the immunoperoxidase bridge technique to the light microscopic localization of C-cells in rat thyroid tissue is described. Guinea pig antisera to rat thyrocalcitonin (TCT) were produced by the injection of highly purified rat TCT (100-300 mouse radius calcifying units/mg) emulsified in complete Freund''s adjuvant. A 1:1000 dilution of the anteserum used in this study gave a strong positive reaction with rat C-cells, and 1 ml of undiluted antiserum provided sufficient material for staining approximately 5000 slides. The substitution of nonimmune guinea pig serum for the anti-rat TCT serum or the prior absorption of anti-rat TCT serum with increasing amounts of highly purified rat TCT both eliminated the staining of thyroid C-cells. Likewise, no staining was observed in tissue sections from rat parathyroid, ovary, pituitary gland and skeletal muscle. Antiserum to synthetic human TCT also could be used to identify rat thyroid C-cells. The method revealed abundant C-cells in goiters from rats fed a low-iodine diet for more than 1 yr. This finding was supported by EM evaluation of goitrous tissue and by the detection, by radioimmunoassay, of TCT in thyroid tissue and in peripheral blood from goitrous rats.