The effects of tannic acid on the in vivo preservation of microfilaments.

A population of single, actin-like microfilaments has been found specifically associated with the cortical microtubules or radish root hairs. Extensive filament bundles are not specifically associated with the tubules although close proximity is observed. A technique is described for obtaining a reliable quantitative estimate of the size of these microfilament populations. The addition of tannic acid to the fixative preserved more microtubule-associated microfilaments, without revealing any extra non-microtubule-associated filaments. Microfilaments preserved with tannic acid have diameters which increase in proportion to the concentration of tannic acid used.