Fig. 3

Intermittent PTH administration enhanced ALP activity and the formation of mineralized nodules. a Representative images of ALP staining of OCCM-30 cells after treatment with vehicle, 1 cycle, 2 cycles and 3 cycles of intermittent PTH. They together demonstrated a progressively enhanced ALP⁺ staining consistent with the increasing numbers of administration cycles. Scale bar: 200 μm. b ALP assay of 0, 1, 2 and 3 cycles of intermittent PTH treated groups. * indicates significant difference between 0 cycle group and other three groups (p < 0.05). c Microscopic findings of the Alizarin red S staining of the control group and the PTH group. The area of observable mineralized nodules in intermittent PTH treated group was obviously larger in comparison with that of the control group. Scale bar: 100 μm. d Alizarin red S extraction assay from the control group and the intermittent PTH treated group. * p < 0.05