UCL Great Ormond Street Institute of Child Health 1 article published in JoVE Biology Immunolabelling Myofiber Degeneration in Muscle Biopsies Maximilien Bencze1,2, Baptiste Periou1, Yasmine Baba-Amer1, Francois J Authier1 1Inserm, Institut Mondor de Recherche Biomédicale, 2The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Program, UCL Great Ormond Street Institute of Child Health Described here is a protocol for direct immunolabelling of necrotic myofibers in muscle cryosections. Necrotic cells are permeable to serum proteins, including immunoglobulin G (IgG). Revealing the uptake of IgG by myofibers allows the identification and quantification of myofibers that undergo necrosis regardless of muscle condition.