Electron-dense deposits in the follicular basal lamina of obese strain chickens with spontaneous hereditary autoimmune thyroiditis. An electron microscopic study.

Thyroid glands of 36 chickens of the obese strain with hereditary spontaneous autoimmune thyroiditis were examined by electron microscopy at 1, 3, 5, 7, 10, and 14 weeks of age with particular emphasis on basal lamina changes. All chickens were of the B1B1 genotype. The electron microscopic results were compared with six normal White Leghorn chickens of the same age. The major abnormality observed in obese strain chickens was the persistent presence of electron-dense deposits along the follicular basal lamina in the thyroid beginning with 7-week-old chickens. The deposits morphologically comparable to immune complexes were noted either between the basal plasma membrane and the follicular basal lamina or below the follicular basal lamina. In 14-week-old chickens, the electron-dense deposits were observed within abnormally thickened basal lamina. The deposits were not present in the vascular basal lamina adjacent to the thyroid follicles and were not observed in the thyroids of 1- to 5-week old chickens and were also not encountered in normal White Leghorn chickens. Indirect morphologic evidence suggests that these may be antigen-antibody complexes, but characterization of these deposits and their role remain to be determined.