Chloride and Pavement Cells in the Gills of Snow Trout, Schizothorax curvifrons Heckel (Teleost, Cypriniformes, Cyprinidae)

The structural characteristics of chloride and pavement cells of the gills of snow trout, Schizothorax curvifrons, were investigated with the aid of the great depth and resolving power of a transmission electron microscope. Ultrastructural analysis showed that the chloride cells were distributed in the filament and interlamellar epithelia. They were circular to elongated in form having a central euchromatic nucleus, expanded tubular system and an abundance of mitochondria with parallel patterns of mitochondrial crests. On the other hand, the squamous to polygonal shaped pavement cells were endowed with irregular nucleus and electrodense cytoplasmic matrix embracing rough endoplasmic reticulum and lesser number of mitochondria, abundant filament bundles and dark vesicles of varying electrodensity. Some of the dark vesicles were bound to the apical plasma membrane of the primary lamellae bearing microridges covered with glycocalyx, however, the apical plasma membrane of the pavement cells of the secondary lamellae did not reveal any signs of the presence of microridges.