Thymic changes in the magnesium-depleted rat.

Summary The effects of a magnesium-deficient diet fed to rats for approximately 65 days have been assessed with special reference to changes in the thymus. The thymus was enlarged in 18 to 52% of deficient animals surviving more than 6 to 7 weeks in various experiments. The remainder demonstrated glands that were smaller than controls. The enlarged thymuses showed marked cellular changes with the normal structure being replaced by cells that morphologically resembled transformed lymphocytes. Of the small glands, 19% had focal or lobular cellular changes similar to those seen in enlarged thymuses. No distant metastases were found and the changes have been interpreted as hyperplastic rather than neoplastic. Prolonged magnesium depletion was accompanied by hypomagnesemia and hypercalcemia or normocalcemia. Marked leukocytosis was present during the early stages of the deficiency. Splenomegaly was consistently found in the magnesium-depleted animals.