Figure 12. Direct stimulatory effect of extracellular phosphate on parathyroid cell proliferation. Response of parathyroid cell growth to increasing phosphate concentrations in the incubation milieu of a human parathyroid cell culture system derived from hyperplastic parathyroid tissue of patients with severe secondary uremic hyperparathyroidism. Determination of cell proliferation by [3H]-thymidine incorporation method. After Roussanne et al (128).