Fig. 4.

Tppp3⁺ cell contribution to bone areas within the HO induction site of the Achilles tendon. a µCT reconstruction of the injured Achilles tendon at 9 weeks post-injury. Heterotopic bone appears red, while native bone appears white (scale bar: 1 mm). b µCT quantification of heterotopic bone volume (BV) of the distal tenotomy site (n = 5 animals per group). c The bone formed area was visualized using H&E staining within representative sagittal sections of the distal tenotomy site. The dashed white line indicates the margins of the remaining tendon tissues. The dashed white box in the upper panels is magnified in the lower panels (scale bar in the upper panel: 200 µm, scale bar in the lower panel: 100 µm). d tdT⁺ cells and Ocn immunohistochemical staining within representative sagittal sections of the distal tenotomy site. The dashed white line indicates the margins of the tendon tissue. The dashed white box in the upper panels is magnified in the lower panels (scale bars in upper panels: 200 µm, scale bars in lower panels: 100 µm). e Quantification of tdT⁺ and Ocn⁺ cells within the bone-formed area (n = 5 animals per group). D: deep; T: tendon. For all graphs, each dot represents a single animal, with the mean ± 1 SD indicated. Statistical analysis for (b) was performed using two-tailed Student’s t test. Statistical analysis for (e) was performed using one-way ANOVA with Tukey’s post hoc test. ^*P < 0.05 and ^**P < 0.01