Skeletal muscle integrity. The primary views in all panels are stained by hematoxylin and eosin. A. Skeletal muscle is shown from an E18.5 untreated control Lifr +/- pup. The insert in the lower right is a PAS stain of a similar view in a Lifr +/+ E18.5 untreated control. Note the absence of fuchsia staining glycogen stores. B. Lifr -/- skeletal muscle from an untreated control littermate displays a separation of the muscle fibers that reveal small vacuoles present within the sarcoplasm (arrows). The insert in the lower right is a PAS stain of a similar view of a Lifr -/- E18.5 untreated control pup. Note fuchsia staining glycogen stores. C. Skeletal muscle from an E18.5 Lifr +/+ pup from a litter where the mother received RU486 on E16.5 and E17.5. D. Skeletal muscle from a RU486 treated Lifr -/- littermate to the pup viewed in panel C. The size bar indicates 100 μm.