Fig. 6.

Tppp3⁺ cells in heterotopic cartilage formed an area at an intracapsular site at 3 weeks after HO induction in a hip postarthroplasty HO model. a Schematic representation of hip HO induction. b Tppp3^ECE/+;R26R^tdT animals were administered tamoxifen (TMx) for three d, followed by a 10 d washout period before HO induction. Reporter activity was examined at 3 weeks after injury. c The cartilage-formed area was visualized using Saf-O/Fast Green staining at the intracapsular site. Cartilage-like matrix appears red. d, e, g tdT⁺ and Sox9 or Acan immunohistochemical staining within representative transverse sections of hips. The image in (d) is the contralateral side, and the images in (e, g) are the injured side of the hips. A acetabulum, FH femoral head, C capsule. f, h Quantification of tdT⁺ and Sox9⁺ or Acan⁺ cells within the cartilage-formed area (n = 4 animals per group). Scale bars: 500 µm. For all graphs, each dot represents a single animal, with the mean±1 SD indicated. Statistical analysis was performed using one-way ANOVA with Tukey’s post hoc test. ^*P < 0.05 and ^**P < 0.01