Skeletal response in rats following the implantation of hypercalcemia-producing Leydig cell tumors.

The effect of Rice H-500 Leydig cell tumor tissue on bone in rats was assessed by morphometric analysis and tetracycline labeling of the lower femoral metaphyses. The rats in which tumor was implanted showed hypercalcemia, increased osteoclastic bone resorption, inhibition of bone formation with reduction in the bone apposition rate, and a loss in trabecular volume compared with the control rats. There was no evidence of tumor metastasis to bone. The results are consistent with the hypothesis that the Leydig cell tumor secretes a humoral factor capable of causing systemic bone resorption.