Specificity: The vast majority of follicular carcinomas of the thyroid will give positive immunoreactivity for anti-thyroglobulin even though sometimes only focally. Poorly differentiated carcinomas of the thyroid are frequently anti-thyroglobulin negative. Adenocarcinomas of an origin other than the thyroid do not react with this antibody. Immunogen: Human thyroid follicular cells (TGB04 & TGB05)