Fate of Lgr5+ Interzone Cells in Developing Synovial Joints
Pregnant mice carrying Lgr5-GFP;R26R embryos were injected with tamoxifen at E13.5, and digit and knee joints of the offspring were collected at E15.5 (A and B), E17.5 (C and D), and 3 weeks postnatal (E and F) for analysis, respectively.
(A and B) Cells in the interzone (IZ) are tagged as shown in embryos at E15.5 in whole mount (scale bars, 1 mm) and sagittal section stained for LacZ+ cells (black arrows; scale bars, 100 μm).
(C–F) Descendant cells at the different stages of cell tracing at the articular surface (Ac) in both digit and knee joints (blue arrows). In the knee, LacZ+ cells are also detected in the meniscus (Me; red arrows), the cruciate ligaments (Cl; yellow arrows), the infrapatellar fat pad (Ifp; green arrows), and the synovial membrane (Sm; orange arrows). Scale bars, 100 μm.