Parafollicular cells.
calcitonin. a polypeptide hormone secreted by the parafollicular or C cells of the thyroid gland; it is involved in plasma calcium homeostasis and acts to decrease the rate of bone resorption. Calcitonin is a hormone secreted by the thyroid gland that reduces the concentration of blood calcium level when it has risen to an above normal level. This polypeptide hormone is made up of 32 amino acids and is produced mainly by the parafollicular cells (also known as C cells) of the thyroid gland. Calcitonin is a hormone that is produced in humans by the parafollicular cells (commonly known as C-cells) of the thyroid gland. Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone. calcitonin. a polypeptide hormone secreted by the parafollicular or C cells of the thyroid gland, which is involved in plasma calcium homeostasis. It acts to decrease the rate of bone resorption. In mammals, the major source of calcitonin is from the parafollicular or C cells in the thyroid gland, but it is also synthesized in a wide variety of other tissues, including the lung and intestinal tract. In birds, fish and amphibians, calcitonin is secreted from the ultimobrachial glands.
http://medical-dictionary.thefreedictionary.com/calcitonin http://www.news-medical.net/health/What-is-Calcitonin.aspx http://www.yourhormones.info/hormones/calcitonin.aspx http://medical-dictionary.thefreedictionary.com/calcitonin http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/calcitonin.html
calcitonin secreted by what cells