Thyroid Follicles: Understanding Colloid and Thyroid Hormone Storage

The thyroid follicles store a viscous, iodine-rich fluid called colloid. The main component of colloid is thyroglobulin, a glycoprotein that contains the iodine-rich hormones thyroxine (T4) and triiodothyronine (T3). These hormones are responsible for regulating the body's metabolism.