Quantification of cytoplasmic glycogen content in smooth muscle cells of arrector pili muscle. The smooth muscle cells were assigned to five categories: 1 - No visible glycogen content; 2 – Scattered glycogen granules; 3 - Large amount of granular glycogen; 4 – Glycogenosomes; 5 – Extensive autophagy, filling a significant part of the cytoplasm. A: A large fraction of smooth muscle cells from Pompe patients shows abnormal forms of glycogen accumulation, while the cells in controls contain mainly no or granular glycogen, which is considered as a normal property for this cell type. (Chi square test: p < 0,0001); B: The number of cells containing glycogenosomes or presenting extensive autophagy is decreased after ERT in the two patients where a follow up biopsy was available. (Significance could not be determined due to the low subject number).