Defining the Complex Epithelia That Comprise the Canine Claw With Molecular Markers of Differentiation

The study investigated the complex epithelial structures of canine claws, which resemble mammalian hair fibers and human nail plates in terms of tissue-specific differentiation. Researchers examined keratin expression in the claws of German shepherd dogs, identifying distinct epithelial cell lineages undergoing hard or soft keratinization. The claw plate was found to have three regions: stratum externum, stratum medium, and stratum internum, with a soft keratinizing epithelium cushioning the underside and tip. The study revealed that the keratinized claw plate expressed hair-specific keratins, while the soft keratinaceous sole epithelium expressed different keratins, including K5, K6, K14, K16, and K17. Two slippage zones were identified, with specific keratin expressions, indicating a complex mechanism of cellular differentiation in canine claws.