Gills of the snow trout, Schizothorax curvifrons heckel: a SEM study

Using the scanning electron microscope, the gills of Schizothorax curvifrons have been studied after carrying out their primary fixation in 2.5% glutaraldehyde in 0.1 M sodiumcacodylate buffer (pH 7.3) for 24 h at 0-4 degrees C and secondary fixation in 1-4% osmiumtetraoxide in 0.1 M sodiumcacodylate buffer (pH 7.3) for 1-2 h at 0-4 degrees C. The gills are observed to comprise of gill arch, gill rakers having minute projections on their inner sides and gill filaments. The filaments originating from the gill arch are in a linear fashion and equidistant from each other, bearing secondary lamellae on both sides of the filament axis and each lamellae running parallel to the adjacent lamellae. The filament epithelium is found to be equipped with pavement cells, mucous cells and chloride cells. The pavement cells have smooth surface with sparse and irregular microridges defining their cell limits. The mucous cells are mainly found on the leading and trailing edges of the filament and the chloride cells are located close to the onset of secondary lamellae. The possible roles of these structures and cells in relation to respiration, water flow and feeding are discussed, setting thereby a platform for further studies in relation to pathology, pollution and stress conditions in aquaculture, natural and polluted environments.