FIG. 3.

Staining of myonuclei and satellite cells in single EDL muscle fibers from adult mice. (a) Muscle fiber from an Hprt1^Cre/+; R26^NZG/+ mouse showing X-gal-stained nuclear profiles under Hoffman optics. Nuclei were confirmed by DAPI staining (b). (c,d) A representative satellite cell on an Hprt1^Cre/+;R26^NZG/+ muscle fiber. The arrowheads indicate an X-gal-labeled satellite cell (c), as identified by immunohistochemistry for CD34 (d). (e,f) Muscle fiber isolated from an Hprt1^Cre/+;R26R mouse. Cytoplasmic β-gal signal from the recombined R26R reporter was observed throughout the myofiber (e). Although satellite cells could be identified by CD34 immunohistochemistry (f, arrowhead), they could not be reliably scored for β-gal expression due to X-gal staining of the muscle fiber cytoplasm. (g–j) Confocal image of a muscle fiber from an Hprt1^Cre/+;R26^NG/+ mouse. (g) Optical section of an intensely EGFP+ muscle fiber. The arrowheads in (g–j) point to an EGFP+ satellite cell, as identified by Pax7 immunohistochemistry (h). (i) DAPI staining. (j) Merged image showing EGFP and Pax7 signals.