Fig. 8. Mechanical stimulation in secondary chondrogenesis. (A-F) e14, (G-H) e11. (A) BrdU labelled at 0 hours, with a 24-hour chase with mechanical stimulation; labelled doublets are observed. (B) osteocalcin (ocn) expression in an adjacent section: ocn is not seen around the SCs (black arrow). (C) BrdU labelled at 0 hours, with a 24-hour chase without mechanical stimulation; again labelled doublets are found. (D) Upregulation of ocn expression around the SCs on an adjacent section (black arrow). (E) BrdU labelled at 16 hours followed by 24-hour chase without mechanical stimulation; labelled cells are found in the germinal region. (F) As E, but with mechanical stimulation; BrdU labelled cells are found in the chondrocyte zone (circled). (G) e11 BrdU pulse at 0 hours followed by a chase for 48 hours without mechanical stimulation, both chondrocytes (blue circle) and osteoblasts (red circle) are labelled. (H) Adjacent section to G, showing ocn expression in BrdU-labelled cells. Scale bars: E, 100 µm; F, 50 µm.