Formation of Intra-Epidermal bodies (IEBs) is associated with giant macrophage-like cells that patrol fish epidermis

Intra-epidermal bodies (IEBs) are large dynamic circular structures that form within fish scale epidermis. IEBs are believed to reflect the sequestering of intra-epidermal debris, such as damaged or dead cells, within the epidermis. The present report describes an association between a giant cell that patrols the epidermis and the formation of IEBs. The giant cell, likely macrophage-related, is a broadly spread cell with lengths up to ~90 μm and average spread areas >600 μm². Time-lapse video microscopy was used to monitor formation of IEBs and determine any association between the IEB and the giant cells. Giant cells were observed to form IEBs, and as an IEB dissipated a giant cell was observed to exit the area previously occupied by the IEB. These observations suggest the IEB is a transitional form of the giant cell, serving as a temporary compartment to isolate and initiate breakdown of the debris scavenged by the giant cell.