Thyroid hormone synthesis involves several steps: 1. Iodide Uptake: Follicular cells actively transport iodide from the bloodstream into the follicle. 2. Thyroglobulin Production: These cells also synthesize and secrete thyroglobulin, a glycoprotein, into the colloid. 3. Iodination and Coupling: Within the colloid, iodide is oxidized and attaches to tyrosine residues on thyroglobulin, forming thyroxine (T4) and triiodothyronine (T3). 4. Release: The follicular cells endocytose portions of the colloid, where lysosomal enzymes cleave T3 and T4 from thyroglobulin, releasing them into the bloodstream.
