FIG. 1.

Cells expressing neural crest reporter transgenes can be identified within long bone preparations of Wnt1-Cre/Rosa26R^YFP and Wnt1-Cre/Rosa26R^LacZ mice but rarely within bone marrow plug aspirates. (A) Whole long leg bones cut open with sharp scissors, as seen under dissecting microscope. Single cells suspensions were obtained by crushing whole long bones and subsequent mechanical and enzymatic dissociation of cells. (B) Fluorescence-activated cell sorting (FACS) plot of single cell suspension obtained from crushed whole bone marrow incubated with trypsin. The 0.022% ± 0.005% (n = 6) of freshly isolated single cells express the YFP reporter. (C) Bone marrow obtained by aspiration of femur, seen under dissecting microscope. Single cell suspensions obtained from such bone marrow aspirates contain only rare YFP+ cells 0.0008% ± 0.0005% (n = 6) as determined by FACS analysis (D), suggesting that such cells are rarely found in the bone marrow. (E) Longitudinal cross section of femur derived from Wnt1-Cre/Rosa26R^LacZ mice viewed under dissecting microscope following X-Gal staining. (F: higher magnification of inset E) X-Gal-positive cells are identified at the boundary between cortex and marrow and along blood vessels within the marrow (blue arrows). (G) Light microscope examination of decalcified long bone sections demonstrates LacZ+ cells between cortex and marrow. Such cells remain adherent to the cortex following bone marrow aspiration. (H) LacZ+ cells are also identified within articular surface of the hip joint of the pelvis of Wnt1-Cre/Rosa26R^LacZ adult mice (dissection microscope: positive cells, blue arrow). (I and J) Cross section of the hip joint (dotted line in H) demonstrates X-Gal-positive cells within articular cartilage (blue arrows).