AN ELECTRON MICROSCOPIC STUDY OF HASHIMOTO THYROIDITIS

¹ Departments of Therapeutics and Anatomy, University of Edinburgh

An electron microscopic study has been made of thyroid tissue obtained from four patients with Hashimoto thyroiditis. Contrary to what has been inferred from earlier light microscopy studies, the basement membrane in Hashimoto thyroiditis is remarkably continuous, taking the form of a single lamina some 50 mµ thick. It differs from that of the normal adult human thyroid in that there is no re-duplication of the membrane. In Hashimoto thyroiditis, temporary gaps in the basement membrane occur which are just sufficient to allow the passage of leucocytes in and out of the thyroid follicles. Small breaks in the basement membrane may occur in necrotic thyroid follicles, and cytoplasmic debris of the epithelial cells then escapes into the stroma.

A mutual activity between invading lymphocytes and the epithelial cells of the thyroid follicles is inferred from the observation that tenuous processes of the epithelial cells embrace the invading lymphocytes and that bulbous lymphocytic processes abut against or invaginate the epithelial cells. It is conceivable that this intimate contact allows antibody bound to the lymphocyte to be directly transferred to the cells of the thyroid epithelium.

Note:

We are grateful to the Wellcome Trust for the permanent loan of the electron microscope and to Mr. J. R. Cameron, Mr. D. McIntosh and Professor M. F. A. Woodruff for their co-operation in providing surgical material.

W. J. I. is in receipt of a grant from the Medical Research Council.