Fig. 1

The heterogenous content of vacuoles in muscles of patients with hypokalemic periodic paralysis. a,b. Haematoxylin & Eosin stained sections from a patient with periodic paralysis (a) and mixed weakness (b) demonstrate vacuoles in many muscle fibres. c,d. Periodic acid Schiffs stain demonstrate that many but not all of the vacuoles in muscles from a patient with periodic paralysis (c) and mixed weakness (d) contain glycogen. e-i. Low magnification transmission electron microscopy (EM) reveal that the vacuoles may have a very heterogenous content, embedded autophagosomes surrounded by glycogen (e), very large autophagosome (f), fibrillar content (g), large accumulation of free glycogen (h) and accumulations of glycogen combined with fibrillar content and membrane-encapsulated glycogen (i). Bar in histology images is 50 µm and in EM images 10 µm