Fig. 1. Lbx1 expression in regenerating skeletal muscles of adult mice. (A-C) Transverse sections of uninjured TA muscles taken from 8-week-old ICR mice immunostained for (A) Lbx1 and (B) M-cadherin and counterstained with Hoechst dye 33342. Note M-cadherin-positive satellite cells do not express Lbx1 (arrows). (E-N) Transverse sections of regenerating TA muscles taken from cardio-toxin-treated 8-week-old mice stained with antibodies against (E,I,L) Lbx1, (J) laminin, (M) M-cadherin and (G) MyoD, and also counter-stained with Hoechst dye 33342. Note most of the cells attached to myofibers are MyoD positive (G, arrows) and also Lbx1 positive (E, arrows). Note that Lbx1-positive cells are located beneath the basal lamina, which is laminin-positive (I-K, arrows). M-cadherin positive cells attached to centrally nucleated regenerating muscles also express Lbx1 (L-N, arrows). (D) Hematoxylin-eosin staining. Several mononucleated cells are seen attached to myofibers (arrows). Bars, 10 µm.