- Thyroid gland tissue
- Parathyroid gland tissue (containing Chief cells which produce PTH)
The Parathyroid gland secretes Parathyroid Hormone (PTH) (Aka: Parathormone, Parathyrin). Caution: Many students mistakenly think Calcitonin comes from this gland, but it doesn’t. Calcitonin comes from the parafollicular cells of the Thyroid gland. PTH causes the intestines to absorb more calcium, the kidneys to retain more calcium, and the osteoclasts to become more active. All will act to increase the levels of calcium ions in the blood.