Time-dependent expansion of marker gene expression. (A-F) Sections of the distal tibial epiphysis of normal Mig-6-flox (A, C, E) and Mig-6-flox;Prx1Cre conditional knockout (Mig-6-cko) (B, D, F) at postnatal Day 5, immunostained with antibodies against Sox9 (A, B); Notch1 (C, D); or the TGFβ1-mediators phosphorylated Smad2/3 (pSmad2/3) (E, F). Immunostaining in the presumptive articular cartilage of the normal Mig-6-flox tibia is limited to a distal portion of the epiphyses (indicated by bars in A, C, E). However, immunostaining is intensified in the presumptive articular cartilage of the Mig-6-cko tibia, and the region of immunostaining is expanded (compare bars in B, D, F to A, C, E). (G-N) Sections of six-week old tibial articular cartilage of normal Mig-6-flox (G, I, K, M) and Mig-6-cko (H, J, L, N) joints immunostained with antibodies against Sox9 (G, H); Notch1 (I, J); pSmad2/3 (K, L) or superficial zone protein (SZP, M, N). Enhanced marker expression by cells in the superficial and middle zones is evident in the six-week-old Mig-6-cko articular cartilage compared to control Mig-6-flox articular cartilage (arrows). Scale bar = 100 nm.
Shepard et al. Arthritis Research & Therapy 2013 15:R60 doi:10.1186/ar4233