An argyrophil III method for the demonstration of smooth muscle cells in light and polarization microscopy.

An esterification with n-butyl alcohol containing 0.5% sulphuric acid (at 56 degrees C, for 16 hours) followed by a treatment in a special physical developer renders smooth muscle cells as well as other contractile elements (striated muscle, cilia, flagella, myoepithel cells) visible in light microscope and birefringent in polarization microscope. A few kinds of non-contractile tissue components without oriented fibrillary structure also stain but do not display birefringence.