Mitochondria-Rich Cells in the Gill Epithelium of Teleost Fishes: An Ultrastructural Approach

Abstract

Publisher Summary This chapter describes the ultrastructure of chloride cells in the gill epithelium of teleostean fishes. It also explores the extent to which changes in water salinity can affect this structure in various species. In teleosts, the gills consist of several branchial archs. Each branchial arch bears several primary lamellae (or filaments), which, in turn, give rise to rows of secondary lamellae. Primary and secondary lamellae are covered by an epithelial sheet, which is subdivided into two regions—namely, (1) primary epithelium covering the primary lamellae and (2) secondary epithelium covering the secondary lamellae. Among the more superficial cells in contact with the outside medium, two types of cells have been regularly identified: the flattened, sometimes piriform, pavement cells and the ovoid chloride cells. The chloride cells are voluminous, mainly encountered in the interlamellar regions of the primary epithelium and on the side of the primary lamella supplied with afferent blood. In the secondary epithelium, the presence of chloride cells is more erratic and may vary according to the fish species. The cytoplasm of chloride cells contain a highly developed membranous system made up of anastomosed tubules. The tubular system extends throughout the whole cytoplasm, except for the Golgi area and a narrow band located just beneath the apical surface.