Molecular and Cellular Characterization of Avian Reticulate Scales and the Evolutionary Development of Skin Appendages in Foot Soles

The study investigated the molecular and cellular characteristics of avian reticulate scales, found on bird foot soles, comparing them to scutate scales and alligator scales. The researchers found that reticulate scales have different Label Retaining Cell (LRC) properties and regeneration abilities compared to other scale types. Unlike scutate scales, reticulate scales do not regenerate after wounding, but instead undergo repair, suggesting that successful skin appendage regeneration requires localized stem cell niches. The study also revealed that reticulate scales do not express β-keratins except for keratinocyte-β-keratin 13. The researchers concluded that the specific molecular and cellular characteristics of reticulate scales in footpads, formed in the developing skin, set up the bio-architectural basis for adult birds to bear their weight and to withstand constant friction.