Whole Teased Fiber Muscle Staining

The method for whole teased fibre staining of extensor digitorum longus (EDL), soleus (SOL) and diaphragm was based on a previously published method (Vanhaesebrouck et al., 2019 (link)) and is given in detail in Supplementary material. For nuclei counting, AChRs were stained with 594-α-BuTx as described above and then individual fibres were teased apart. Fibres were mounted in Confocal Matrix containing DAPI onto microscopy slides, which were then coded so that the image acquisition and analysis were carried out blinded. Stained muscles were visualized using an Olympus IX71 wide-field fluorescence microscope. Images were captured using Simple PCI (Digital Pixel) and analysed using ImageJ. Number of mice used for each analysis was as described in the figure legends.