Spontaneous thyroiditis in the obese strain of chickens. IV. The effect of thymectomy and thymo-bursectomy on the development of the disease.

Abstract

White Leghorn chickens of the Obese Strain (OS) were thymectomized and thymobursectomized on the day of hatching. Histologic examination of the thyroid glands of the thymectomized group, 7 weeks after hatching, revealed a significant increase in the frequency and severity of spontaneous chronic autoimmune thyroiditis as compared to untreated OS controls. In the sera of both untreated and thymectomized OS chickens precipitating thyroglobulin antibodies were demonstrable in most cases. However, hemagglutinating thyroglobulin antibodies occurred in somewhat lower frequency and in lower titers in thymectomized animals than in untreated controls. Sham thymectomies had no effect. Thymo-bursectomy on the day of hatching had a slightly inhibiting effect on the development of spontaneous chronic thyroiditis in OS chickens when examined 7 weeks after hatching. This suppressive effect was less pronounced than the one found previously with bursectomy alone. Circulating thyroglobulin antibodies could be demonstrated only in a few sera of the thymobursectomized group. The results suggest a controlling function of the thymus on the self-recognition mechanism in chickens and support the earlier findings that bursa-dependent cells play the major role in the development of spontaneous chronic thyroiditis in OS chickens.