Fig. 1

Structural characteristics in the Cor, BC, and FC of trout OM. a Trout and its eye enlargement. b H&E stain of trout eye. c Schematic diagram of the existence of three distinct regions on trout OM. d TEM (upper) and scanning electron microscope (lower) of the three distinct regions of control trout OM. From left to right: Cor, BC, and FC. Red stars indicate goblet cell orifices, red arrowheads indicate goblet cells, red arrows indicate microvilli. Scale bar, 2 μm. Enlarged images shown in (d, upper) refer to control trout OM. e Scanning Electron Microscope of microorganisms in three regions of the Cor (upper), BC (middle), and FC (lower) of control trout OM. Red arrowheads indicate commensal microbiota. Scale bar, 1 μm