Mitochondria-rich cells in gills of tilapia (Oreochromis mossambicus) adapted to fresh water or sea water: quantification by confocal laser scanning microscopy
Journal of Experimental Biology
We used confocal laser scanning microscopy to validate a new and fast co-labelling method to study the distribution of mitochondria-rich (MR) cells in gill filaments and to differentiate between MR cells that are in contact with the water (cells labelled with both DASPMI and Concanavalin-A) and those that are not (DASPMI-positive only). This method was used to describe differences in MR cell density that occur in the gills of tilapia Oreochromis mossambicus adapted to fresh water or sea water.
... n fresh water, the total MR cell density was 6233 cells mm-2 and the density of the subpopulation of MR cells that are in contact with the water was 3458 mm-2. After seawater adaptation, cell density decreased to 3061 cells mm-2 for all MR cells of which 2445 cells mm-2 were in contact with water. The percentage of double-labelled MR cells in the total MR cell population had increased from 55 to 80 %. MR cell size (measured as the maximal cross-sectional area) increased from 87 µm2 in fresh water to 217 µm2 in sea water. Biochemical determination of specific and total Na+/K+-ATPase activity in gill homogenates showed no difference between freshwater- and seawater-adapted fish. Quantification of 'mature' chloride cell density in fixed gill filaments using scanning electron microscopy resulted in an overestimate of chloride cell density due to shrinkage of the sample.