Observation on the fine structure of the gill in Pangasius sutchi

The f ine structure of the gill in Pangasius sutchi has been investigated using transmission and scanning electron microscopy. The terminal of gill filament of Pangasius sutchi expands to be spoon-shaped. Many secondary gill lamellae arrange on two sides of each f ilament, and inlay each other. There are many taste buds distributing on the surface of gill arches and gill rakers. The respiratory surface of gill f ilament is rough and highly full of bloodvessels; the non-respiratory surface of gill f ilament is composed of tetragonal or hexagonal epithelial cells, which form various patterns. There are many holes among the circular ridgy patterns. The basic structure of the secondary lamellae consists of one or two outer epithelial layers, an intermediate basement membrane layer internal to which are the pillar cells and their f langes which line the blood channels. The chloride cells are frequently found in the base regions of the secondary lamellae and are overlain by a single epithelial layer , they often seemed to be open at the surface between adjacent epithelial cells. The relationships between the special structure of f ish gills and their funct ion are discussed.