4.4. Histology

Mouse hearts were cut longitudinally and fixed in 10% phosphate-buffered formalin and embedded in paraffin for histological analysis. Five micron sections were stained with hematoxylin and eosin (H&E) to detect inflammation, picrosirius red to detect collagen or toluidine blue to detect mast cell granules. Myocarditis and fibrosis were assessed as the percentage of the heart with inflammation or fibrosis compared to the overall size of the heart section using a microscope eyepiece grid, as previously described [22,83,88,97]. Sections were scored by at least two individuals blinded to the treatment group.