Question

Thyroid hormones synthesized in cuboidal epithelium are stored as

• A. Tyrosine molecules in follicular cells
• B. Thyroglobulin colloids in lumen
• C. Iodine molecules in lumen
• D. None of the above

Answer 1

The correct option is B

Thyroglobulin colloids in lumen

The thyroid hormones are stored as thyroglobulin colloids in the thyroid lumen. Large numbers of closed follicles are filled with a secretory substance called colloid. The major constituent of colloid is the large glycoprotein thyroglobulin. The endoplasmic reticulum and Golgi apparatus synthesize and secrete the thyroglobulin into the follicles. Thyroglobulin contains the thyroid hormones, T3 and T4, within its molecule.