A study of staining at different pH values showed that the fibre became decreasingly basiphil at successively higher levels. This was supported by an increased reaction for basic groups after keratinization, although a reaction for acid groups was obtained in the normally basiphil pre-keratinization region, and the keratinized fibre after vigorous treatment.
The reactions for individual amino-acid residues are probably not quantitative, but indicate availability to react. The strongest reaction for arginine was in the trichohyalin of the medulla and inner sheath, for tyrosine and tryptophan in the keratinized part of the fibre, and for histidine in both the keratinized and unkeratinized parts.
Most reactions gave asymmetrical results, but vigorous treatment tended to produce uniform results. This supports the suggestion that the asymmetry is due to differences in accessibility rather than to chemical differences.
- Copyright © 1959 The Company of Biologists Ltd.