Representative microscopic images of muscle pathology for a patient with infantile-onset Pompe disease.

<p>(A) Tissue samples, obtained before ERT at age 10 days, processed in paraffin and stained with hematoxylin and eosin: numerous large empty intracytoplasmic vacuoles (indicated by arrows) are present in the muscle fibers. (B) Muscle tissue corresponding to same origin as in (A) (obtained before ERT at age 10 days) but processed in epoxy resin for high-resolution light microscopy (HRLM) and stained with periodic acid-Schiff/Richardson’s stain. Note the deep purple glycogen granules (arrow). (C) Few empty vacuoles (arrows) were observed in the muscle fibers (processed in paraffin and stained with hematoxylin and eosin) from the same patient after ERT for 6 months. (D) Muscle tissue obtained post-ERT corresponding to the same origin but processed in epoxy resin for HRLM and stained with periodic acid-Schiff/Richardson’s stain. Few purple glycogen granules (arrow) remained after ERT treatment.