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Figure 4. Froglet blastema has a permissive environment for survival and differentiation of muscle precursor cells. A,B:Xenopus limb muscle tissue in the adult frog possesses Pax7-positive cells (A, fluorescein isothiocyanate [FITC] in blue–green); a transverse section of the muscle tissue was stained with anti-laminin (FITC in green) and anti-Pax7 (rhodamine in red) antibodies, and a high magnification of a section shows that a Pax7-positive in red is located inside basal laminae visualized by anti-laminin immunoreactivity in green (B). C–K: Cells isolated from muscle tissue of froglet femora were cultured for 1 day and stained with anti-Pax7 antibody. C: In low cell density, many cultured cells were Pax7-positive (C, insert, diaminobenzidine staining in brown). D: After 10 days incubation, a lot of elongated multinucleate cells were MF20-positive. E: An overlap image of bright and fluorescent field embosses implanted cell aggregates that contain 1 day-cultured Pax7-positive cells from cmv–green fluorescent protein (GFP) transgenic frogs. F–J: After 14–21 days, samples were stained with anti-GFP (F,I) and MF20 (G,J) antibody; a brightfield view (H). F,I: GFP-positive cells were recognizable in the blastema (arrows and arrowheads). F,G,I,J: Some GFP-positive cells were MF20-positive (arrowheads), and other ones were MF20-negative (arrows). K: The 4′,6-diamidine-2-phenylidole-dihydrochloride (DAPI) staining (blue) shows that some of these double-positive cells are multinucleate (arrowheads). Scale bars = 400 μm. |