Image capture
Images of immunostained muscle fibres were captured using a Spot-RT slider (SPOT Imaging Solutions: Diagnostic Instruments, Inc., Sterling Heights, MI) cooled digital microscope camera mounted on a compound widefield fluorescence microscope (Olympus BX-50, Olympus Corporation, Tokyo, Japan) equipped with a CoolLED illuminator (CoolLED Ltd, UK). Illumination and exposure times were optimized for each antibody and kept consistent throughout the acquisition. The Alexafluor 594 was excited using Olympus U-MWIY (540-580 nm) excitation filter, the Alexafluor 488 and UEA-I-FITC were excited using Olympus U-MWIG (465-495 nm) excitation filter and the WGA-350 was excited using narrow band UV filter (Olympus U-MNU-BP, 330-385 nm). All images were taken using a 20 × oil immersion objective.