Fig. 3. Lbx1 expression in activated satellite cells. (A-C) Satellite cells freshly isolated from EDL muscles were cultured in satellite cell growth medium for 4 days and then immunostained for Lbx1, MyoD, Pax7 and myogenin, and also counter-stained with Hoechst dye 33342 to identify nuclei. (A) Sphere-shaped cells expressing Pax7, a marker for activated satellite cells, also show high levels of Lbx1 (arrowheads). (B) Sphere-shaped cells expressing MyoD, a marker for activated satellite cells, show high levels of Lbx1 (arrowheads). (C) Sphere-shaped cells that express Lbx1 do not express myogenin (arrowheads). Bars, 50 µm. (D,E) Satellite cells freshly isolated from (D) trunk or (E) diaphragm muscles were cultured in satellite cell growth medium, and then immunostained for Lbx1, Pax7 and MyoD. Note that MyoD- and Pax7-positive satellite cells express Lbx1. Arrowheads indicate Lbx1⁺/MyoD⁺ satellite cells (upper panels) or Lbx1⁺/Pax7⁺ satellite cells (lower panels). Bars, 10 µm.