Fig. 3.

Induced PTEN deficiency in adult articular chondrocytes causes OA phenotypes in mice. a Schematic diagram showing the protocol of tamoxifen administration for starting ROSA^EYFP expression or ablating the PTEN gene in articular chondrocytes. Five successive doses of tamoxifen were injected every day since 22-day-old. Knee joints were analyzed at 27 days, 2 months and 8 months of age. b Representative images of immunohistochemical staining of EYFP in articular cartilage from 27-day-old Ctrl and iROSA^EYFP mice (n = 3 per group). Tamoxifen was injected since 22-day-old. The framed area in each picture is shown below at a higher magnification. c Representative images of safranin O staining of hind limbs from 2-month-old Ctrl and iPTEN^fl/fl mice (n = 4 per group). Tamoxifen was injected since 22-day-old. d Representative images of safranin O staining of knee joints from 8-month-old Ctrl and iPTEN^fl/fl mice (n = 12 per group). Tamoxifen was injected since 22-day-old. The framed area in each picture is shown below at a higher magnification. e Quantified pathological changes of each group at 8 months. Each value represents the mean ± SEM (n = 12 per group). **P < 0.01. Scale bars: 250 µm in (b) and (d), 800 µm in (c)