Microridges in Cyprinus carpio scale epidermis

Actin‐based microridges were evaluated in koi scale epidermis in situ. The fingerprint‐patterned microridges covered the dorsal face of superficial layer cells and were overall similar to that described in many fishes. Several other microridge patterns were observed, however, ranging from loose or tightly packed ridges, fragmented ridges, a honeycomb ridge pattern and the presence of actin‐rich puncta. Individual F‐actin‐stained microridges varied greatly in length, from a few to 30 μm or more, with a few single ridges extending the entire perimeter of a cell. Branched microridges, comprised of single ridges that appeared continuous with each other, extended to over 150 μm in some cases. The actin‐binding proteins α‐actinin and cortactin were distributed in a dot‐like pattern along the length of individual ridges, consistent with bundled actin cores described in earlier studies. Antiphosphotyrosine antibody failed to detect this signal transduction‐related amino acid modification in microridges unless tyrosine phosphatases were first inhibited, after which bright phosphotyrosine‐rich dots were detected along the microridges.