Figure 3.

Satellite Cells in the G1 Phase Revert to the Quiescent-like State

(A) A schematic illustrating the experimental procedure. To determine whether activated satellite cells are reversible to the quiescent-like state without cell division, individual myofibers were freshly isolated from EDL muscles and cultured in DMEM with or without damaged myofibers for 48 h, as shown in Figure 2. Damaged myofibers and culture media were then removed and intact myofibers were maintained in fresh DMEM for a further 24 h.

(B and C) (B) Immunostaining of satellite cells associated with myofibers for PAX7 and MYOD was performed (quantified in C). (D, DD, Dam, and DamD: n = 3, 3, 5, and 5 mice, respectively; >15 individual myofibers per mouse were counted.) Scale bars, 50 μm. Asterisk (^∗) indicates differences among Dam and DamD conditions (p < 0.05).

(D and E) (D) Immunostaining of satellite cells associated with myofibers for PAX7 was performed (transverse diameter of satellite cells on myofiber quantified in E). Yellow lines indicate transverse diameter of satellite cells. (n = 3 mice per condition; at least 11 cells per mouse were counted.) Scale bars, 25 μm. Asterisk (^∗), pound sign (#), and dagger (†) represent differences among plating medium (PM) and either D, Dam or DamD; D and Dam; or Dam and DamD, respectively (p < 0.05).