ollicles the functional Units of the Thyroid Gland Section of thyroid gland Follicles are the sites gael sobdoder Where Key Thyroid e Elements Function. 必 Thyroglobulin (tg) Tyrosine lodine Thyroxine ( T4) Colloid Triiodotyrosine(T3) c cell FollicularFollicles: the Functional Units of the Thyroid Gland Follicles Are the Sites Where Key Thyroid Elements Function: • Thyroglobulin (Tg) • Tyrosine • Iodine • Thyroxine (T4) • Triiodotyrosine (T3)