p27 expression (brown color) in asymptomatic (af) and symptomatic females (sf) at the ages indicated. Dashed boxes indicate areas shown in detail. A) Muscle fibers distant from the levator ani fascia show no cytoplasmic p27 expression. Inset shows strong staining of plasma membrane and adjacent nucleus (arrow). B) Some fibers adjacent to the levator fascia (If) often show weak cytoplasmic staining, but normal cell size (n). C) Hypertrophy of muscle fibers (h) is accompanied by variable p27 cytoplasmic expression (from none to moderate). D) Variable size of muscle fibers. Strong cytoplasmic staining accompanies regression of myotubes (arrow and dashed box). E) Regression of muscle fibers (arrows) is associated with cytoplasmic vacuolization (arrowheads in inset) and expanded stromal component (s). F) Expanded muscular stroma (s) contains remnants of muscle fibers (arrows). Inset shows control staining (cs). Bars in insets: vertical = 10 μm, horizontal = 50 μm.