Immunohistochemical Demonstration of Keratins in the Epidermal Layers of the Malayan Pangolin, with Remarks on the Evolution of the Integumental Scale Armour

The study used immunohistochemistry to examine the distribution of various keratins in the epidermis of the Malayan pangolin (Manis javanica), revealing region-specific differences in keratin expression. Pan-keratin showed varying intensities, with strong reactions in the abdominal epidermis's outer layers and positive reactions in the dorsolateral epidermis's vital layers. Specific keratins like CK1 were present in all epidermal layers except the ventral stratum corneum, while CK5, 6, 9, and 10 were limited to the soft ventral epidermis. Hair keratins AE13 and AE14 showed distinct patterns, with AE13 in the dorsal granular layer and AE14 in the abdominal stratum basale and hair follicle root sheath cells. These findings were discussed in the context of the evolutionary development of the pangolin's dorsal scales, suggesting an origin from the tail root extending towards the head.