Cross sections (5 µm thick) of the zebrafish skin, 40×, scale bar 40 µm. These sections were stained with Mallory and AB/PAS. Mallory staining highlighted rounded, oval, and elongated CCs (arrows) in the intermediate layer of the epidermis with central acidophilic cytoplasm and spherical basophilic nucleus. Keratinocytes (*) are evident in the superficial stratum. The mucous cells (arrowheads) are located mainly in the superficial and medium layers, AB/PAS positive and appear purple, while CCs are AB/PAS negative, with a dark central nucleus.

Longitudinal sections (5 μm thick) of zebrafish skin, Sections are immunohistochemically treated with MAPK p38. Immunoperoxidase counterstained by H, 100×, scale bar 100 μm. Immunofluorescence, 40×, scale bar 40 μm. Immunoreactive CCs for MAPK p38 (arrows) appear evident, with a large core centrally located. They are well organized in the intermediate epidermal layer as shown by counter colouring with H.

Cross sections (5 μm thick) of zebrafish skin. Sections are immunohistochemically treated with TLR2 and Piscidin1. Immunoperoxidase 40×, scale bar 40 μm. There are distinct CCs for TLR2 and Piscidin1 (arrows), with a significant core in the middle. They are neatly organized in the middle epidermal layer.

Cross sections (5 μm thick) of zebrafish skin. Sections are immunohistochemically treated with MAPK p38, TLR2, Piscidin1, 5-HT, and iNOS. Immunofluorescence 20×, scale bar 20 nm. Clear CCs immunoreactive for antibodies tested (arrows) are evident. TL = Transmitted Light.

Cross section (5 μm thick) of zebrafish skin. Colocalization of antibodies tested. Immunofluorescence 20×, scale bar 20 nm. CCs immunopositive are colocalized for antibodies tested (arrows). The “display profile” function confirms these data. TL = Transmitted Light.