Fig. (8) Diagram of the parathyroid functional cytology. Chief cells undergo periodic changes between active and inactive stages corresponding to extracellular environments. Oxyphil cells derived from chief cells are seen in elderly or some metabolic derangements. The presence of water-clear cells is associated with parathyroid hyperplasia or adenoma. Mast cells (MC), macrophages (Mp), and lipid storing cells (LSC) signal towards chief cells to affect parathyroid function.