The ultrastructure of chloride cells in the gills of the teleostOreochromis mossambicus during exposure to acidified water

Abstract

Summary. Branchial chloride cells, which actively take up ions in the gills of freshwater fish, were studied in tilapia {Oreochromis mossamhicus) exposed to sublethally acidified freshwater. Structural damage of cells, result ing in cell death by necrosis, only occurred transiently, when the reduction of water pH was acute rather than gradual. The most prominent effects of water acidifica tion were the rapid increase in the num ber of chloride cells and the changes in frequency of the different stages of the chloride cell cycle. In the opercular inner epitheli um, a twofold increase in cells occurred 48 h after gradu al acidification. Cell density stabilized after 4 weeks at a level 5 times that of control fish. Four transitory stages were distinguished in the chloride cell cycle: accessory or replacement cells, immature, mature, and degenerat ing (apoptotic) cells. In control fish, m ature chloride cells dom inated (over 50%) with immature and apoptot ic cells totalling about 40%. After 4 weeks in acid water, only 13% of the cells were mature. Immature and apop totic cells dominated, each representing about 40% of the total num ber of chloride cells. M ature cells apparent ly age rapidly under these conditions. Thus, chloride cells turn over quickly in acid water, with a minor in crease in ion transport capacity of the gills. This conclu sion is supported by the observation that opercular and branchial Na + / K + ATPase activities in treated fish are only 4 0 % -5 0 % higher than in controls.

Chloride cells and pavement cells in gill epithelia of Acipenser naccarii: ultrastructural modifications in seawater‐acclimated specimens

“…The ultrastructural differences that were detected are a consequence of their acclimation to salinity. Ultrastructural studies of other fishes, however, have found more than one type of chloride cell, distinguished by the different electrodensity of their cytoplasm (Doyle & Gorecki, 1961; Wendelaar Bonga et al ., 1990) or by their different localizations and apical membrane characteristics (Pisam et al ., 1987, 1995, 2000; Pisam & Rambourg, 1991). The series of projections of the apical plasma membrane in chloride cells of gill epithelium of A. naccarii and the clear vesicles in their subapical cytoplasm are characteristic of type α chloride cells (Pisam et al ., 1995).…”

Changes in distribution, morphology and ultrastructure of chloride cell in Atlantic salmon during an AGD infection

“…Chloride cells are believed to be the primary extra‐renal site for regulation of osmotically active ion concentrations, ultimately helping to regulate blood pH by manipulating the rates of Cl − and Na + ionic uptake, the activity of which mediates transfer of H + and HCO 3 − (Evans, Piermarini, & Choe, ; Laurent & Dunel, ). Apoptosis of CCs in teleosts has been previously described under both pathogenic conditions, that is toxicants in the rainbow trout ( O. mykiss ) (Daoust, Wobeser, & Newstead, ; Mallat, ) and under physiological conditions in newly hatched rainbow trout (Rojo & González, ), newly hatched brown trout ( Salmo trutta ) (Rojo, Blanquez, & Gonzalez, ), the adult Mozambique tilapia ( Oreochromis mossambicus ) (Wendelaar Bonga, Flik, Balm, & van der Meij, ; Wendelaar Bonga & van der Meij, ) and the hybrid O. mossambicus × Oreochromis urolepis hornorum (Sardella, Matey, Cooper, Gonzalez, & Brauner, ). These authors all report the ultrastructural changes in MRCs as showing nuclear and cytoplasmic condensation and enlargement of the mitochondria surrounded by a distended tubular system and oedematous areas, as reported in the current study.…”

Confocal scanning laser microscopy with complementary 3D image analysis allows quantitative studies of functional state of ionoregulatory cells in the nile tilapia (Oreochromis niloticus) following salinity challenge

“…The classical model of MRC function holds that only “mature” cells, that is, those in contact with the external environment via an apical pit or crypt, are involved in ion transport (Wendelaar Bonga and van der Meij, ; Wendelaar Bonga et al, ). Conventional quantification methods using fluorescent probes of mitochondria, for example, DASPEI and its analogue DASPMEI or anti‐Na + /K + ‐ATPase do not give an accurate estimation of the dynamics of MRC function and distribution following transfer as they do not differentiate between developmental stages of MRCs, labeling all MRCs within the target tissue regardless of functional state, leading to an overestimation in density of functional ion‐transporting cells.…”