Iridescence in striated skeletal muscle may be seen if muscle fibres are transected perpendicularly to the long axes of muscle fibres. I think it may originate from multilayer reflective interference from A and I bands. It can be found from fish to mammalian muscle and in processed meat where treatments have preserved A band reflectance.. I have spent a few weeks looking for iridescence in dry-aged beef - but nothing yet. This makes sense to me because autolysis may have disrupted reflective A bands - all those discoveries of Z-line, alpha-actinin, thin filament insertion, etc. being disrupted by autolysis. But negative findings are a real weakness in the scientific method - maybe aged beef exhibits iridescence but I failed to find it. So, has anyone seen iridescence in dry-aged beef? It is perhaps important for anyone interested in meat colour. Light scattering has a strong effect on the colourimetry of fibres - from meat myofibers to textile fibres. In meat myofibers, the pH-dependent effect on lateral scattering is well documented - but much work remains for light passing along myofibers (they act like optical fibres). Can you help?