Morphological changes of mitochondria-rich cells in gill of Sparidentex hastaduring adaptation to different environmental salinities by scanning electron microscopy

To determine the cellular and adaptations changes in mitochondria -rich cells under different environmental salinities, Sparidentex hasta as a urihaline has been studied.180 fish weighing 150 ± 0.5 gr and 23±1 cm length, were directly exposure to (5 , 20 , 40 and 60ppt) salinitiesfor a week.Sampling was performed on days 1,2 and 7 and three fish from each tank ( 12 fish from each treatment ) were cached at each time. After preparing, samples fixed in glutaraldehyde 2/5 % solution and washed with 0.1M (pH=7.4) buffer phosphate. Samples were dehydrated in increasing ethanol series ( from 50 % to pure ethanol )followed by 100 % acetone.Tissue blocks were frozen by liquid nitrogen and then immediately followed by scanning electron microscope LEO ( Model 1455VP) with the voltage 15Kv. The upper levels of mitochondria -rich cells under scanning electron microscope revealed according to the apical openings, three types of mitochondria -rich cells derived apertures, shallow and deep recognizable.The number and size of mitochondria -rich cells in the apical openings in 60ppt salinity increase on the first day compared to rest of the treatments .During the experiment, the density and size of the openings in the mitochondria -rich cells in the lower salinity of the sea water was increased but in higher salinity of sea watersize and density of openingsincreased during experimental time.