THE LONG-TERM EFFECT OF A CALCIUM DIET ON THE BONE TISSUE, C-CELLS AND PARATHYROID-GLANDS OF THE RAT

In this experiment of 11 month-duration, 18 female Wistar rats receive d controlled amounts of calcium with food and water, to produce a stat e of either hypocalcemia or hypercalcemia. After a long-term low calci um diet hypocalcemia disappeared. This group of animals showed insigni ficant increases in the nuclear-cytoplasmic ratio of the parathyroid c ells as well as in the total volume of the parathyroid glands, and a s ignificant increase in the volume density of the osteoid. In the group receiving a high calcium diet, hypercalcemia was still present after 11 month. The insignificantly smaller and more numerous C-cells produc ed more calcitonin than normally. The parathyroid cells were significa ntly smaller and the numerical areal density of the osteoclasts was si gnificantly lower than in the control group. It can be concluded that the parathyroid glands and C-cells are involved in the maintenance ot blood calcium homeostasis during a long-term experiment on rats receiv ing low or high calcium diet.