ABSTRACT
Parathyroid Glands and PTH The parathyroid glands are found in all air-breathing vertebrates, and appear first in amphibians coincident with their transition to terrestrial life (Ch.72). Investigators have suggested that the appearance of parathyroid glands may have arisen from a need to protect against the development of hypocalcemia, as well as the necessity to maintain skeletal integrity. Terrestrial animals, compared to their aquatic cousins, live in a relatively low calcium, high phosphate environment.
