Thyroid hormone production
1. Follicular cells of thyroid stimulated by TSH to make thyroglobulin, which goes to the colloid.
2. In colloid, tyrosine residues of thyroglobulin are iodinated and form mono- and diiodotyrosine, precursors of triiodothyronine and thyroxine (thyroid hormones).
3. Mature thyroglobulin molecules are endocytosed back into follicular cells, where the thyroid hormones are cleaved off and enter circulation.