Some limitations of the use of tannic acid as a marker of damaged skeletal muscle fibres.

Mouse biceps brachii muscles containing single transverse incisions were treated with low molecular weight tannic acid. In the absence of fibre degeneration, intracellular spread of tannic acid was confined to a short distance along the fibres from the damaged portions of the cell membranes. Beyond this, damaged and undamaged fibres could not be distinguished from one another. Tannic acid is not a reliable marker of localized trauma to skeletal muscle fibres.