Ziehl-Neelsen's Stain for Skin Sections to Show Wool and Hair Follicles

The study by Lubow A. Margolena explores the use of Ziehl-Neelsen's carbol-fuchsin stain to differentiate between the keratin of the medulla and cortex in hair shafts from skin sections of sheep and goats. The method involves staining deparaffinized, hydrated sections of Bouin-fixed or formalin-fixed skin for 20-24 hours at 25°C, followed by decolorization and counterstaining with Harris' haematoxylin. The medullary keratin appears colorless or orange (if orange G is used) against a dark red acid-fast cortex. This staining technique is useful for studying follicular development, taxonomic classification, and evaluating wool and mohair quality, as medullated wool and hair are undesirable for manufacturers. The study highlights the chemical and physical differences between medullary and cortical keratins, which affect their staining reactivity.