Microscopic Studies on the Structure and Composition of Keratin Fibers1

Abstract

The distribution of cystine sulfur in the cortex of various animal fibers has been investigated by the staining of cross sections with mercury vapor. The receptivity to dyes of various portions of the cortex has been found to be inversely related to their sulfur content. After oxidation with peracetic acid or bromine, the cystine-rich portion of the cortex in bilateral fibers (the paracortex) swells more in aqueous solutions than the orthocortex. Fibers so oxidized swell greatly in dilute, neutral or alkaline, solutions of strong electrolytes; the swelling is repressed at higher salt concentrations.