The Keratins of the Human Beard Hair Medulla: The Riddle in the Middle

The study explored the complex keratin expression within the medulla of human beard hair, identifying a unique co-expression of 12 hair keratins and 12 epithelial keratins, which is more than any other human epithelial structure. It was discovered that these keratins can form intermediate filaments with various pairing partners, indicating a dynamic assembly process. The presence of cortex-like cells within the medulla was also noted, suggesting a potential functional role. The study highlighted the heterogeneity of keratin composition and the promiscuity of keratin pairing in the medulla, which could have implications for understanding hair biology and disorders. The research involved analyzing hair follicles from three individuals using immunofluorescence microscopy, electron microscopy, and in situ hybridization, and was supported by the Friedrich Sander Stiftung without any conflicts of interest.