Calcitonin is produced by which thyroid cell type?

Calcitonin is produced by which thyroid cell type?

• A. Parafollicular C cells
• B. Follicular cells
• C. Parafollicular D cells
• D. Follicle-lining cells

Answer: (A)

Calcitonin is produced by the parafollicular cells, the C cells, in the thyroid. These cells are located between the thyroid follicles and release calcitonin in response to high blood calcium, helping to lower calcium levels by inhibiting osteoclast-mediated bone resorption. The follicular cells lining the follicles, in contrast, synthesize and secrete thyroid hormones (T3 and T4) and do not produce calcitonin. There isn’t a thyroid cell type called parasympathetic “D” cells, so that option doesn’t apply. In short, calcitonin comes from the parafollicular (C) cells.

Calcitonin is produced by the parafollicular cells, the C cells, in the thyroid. These cells are located between the thyroid follicles and release calcitonin in response to high blood calcium, helping to lower calcium levels by inhibiting osteoclast-mediated bone resorption. The follicular cells lining the follicles, in contrast, synthesize and secrete thyroid hormones (T3 and T4) and do not produce calcitonin. There isn’t a thyroid cell type called parasympathetic “D” cells, so that option doesn’t apply. In short, calcitonin comes from the parafollicular (C) cells.