Physiology & Biochemistry · single question
Where is thyroid hormone (T3 and T4) stored in the thyroid gland?
Show answer and explanation
Correct answer: C. Follicular cells (within thyroid colloid)
- A. Incorrect. Parafollicular C-cells (clear cells) produce calcitonin for calcium regulation — they are a completely different cell population from follicular cells.
- B. Incorrect. The hypothalamus produces TRH to regulate the pituitary-thyroid axis but does not store thyroid hormone.
- C. CORRECT. Thyroid hormones (T3 and T4) are synthesized as thyroglobulin and stored within the colloid of follicular cells in the thyroid gland. Upon stimulation by TSH, thyroglobulin is cleaved and T3/T4 are released into the bloodstream.
- D. Incorrect. The anterior pituitary produces TSH, which stimulates thyroid hormone synthesis — it does not store T3/T4.
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