TMJ tissue samples collected from control and TMJ OA mice were fixed in 4 % PFA overnight, decalcified with 4.5 % EDTA for 28 d, paraffin-wax embedded, and sectioned at 8 μm. Sections were stained using a Mason’s Trichrome. For immunohistochemistry, sections were dewaxed, treated with 132.2 mmol/L sodium borohydride, permeabilised with methanol and 0.5 % Triton (v/v), blocked in 5 % donkey serum (D9663, Sigma-Aldrich, St. Louis, MO, USA) for 2 h, and incubated with primary antibodies against either MMP-13 (1:200, AB39012, Abcam, Branford, CT, USA) or NG2/CSPG4 ectodomain (1:200, AB5320, Sigma-Millipore, Santa Cruz, CA, USA). All secondary labelling was with Alexa Fluor donkey anti-mouse 488 and donkey anti-rabbit 568 (1:500, Invitrogen, Invitrogen, Carlsbad, CA, USA). Nuclei were labelled with DAPI (D9542-1MG, 1 μg/μL, Sigma-Aldrich). Sections were imaged using an inverted fluorescent microscope using a 10 × objective (DMI6000B, Leica, Buffalo Grove, IL, USA). Laser intensity, gain, and magnification were standardised for all acquisitions. Brightness and contrast settings were standardised for all images during post-processing. Acquisition settings were verified using control stains containing no primary antibody or isotype control (Reed et al., 2022 (link); Yotsuya et al., 2019 (link)). All images are representative of 4 biological replicates for each experimental group.