[Dense material observed in pericapillary space of the thyroid of Hashimoto's disease].

An electron microscopic observation was performed on the follicular capillary of thyroid of Hashimoto's disease. Material was the thyroid obtained from a 41-years-old female showing typical features of this disease both clinically and histologically. Some remarkable findings were the presence of multi-layered basement membrane like structure, and the accumulation of dense minute granular materials concerning with long processes of lymphcyte in the widened pericapillary space. From the above-mentioned findings, it was postulated that there was abnormal transport on follicular basement membrane-pericapillary space-endothelial basement membrane system.