Renal histomorphological responses in adaptation to different environmental salinities in Sparidentex hasta

Water and electrolyte balance is vital for aquatic organisms in both hyper and hypo osmotic environments. Kidneys as excretory organs play an important role in osmoregulation and body fluid homeostasis. In this study a total number of 180 Sobayti (Teleost: Sparidentex hasta) were exposed to different salinities to assess changes in the kidney structure and alterations in plasma levels of electrolytes, glucose and cortisol. Salinity challenges were examined for a period of 14 days in four experimental groups: 40ppt as control and 5, 20 and 60 ppt as other experimental treatments. 24 hours after salinity challenge, significant changes were observed in the lumen diameter of the primary proximal tubule at the sections from trunk kidney in both 5 and 20 ppt conditions (P<0.05). Lumen diameter of the second part of the proximal tubule did not differ in any of the experimental salinities (P>0.05).However, lumen diameter of the distal tubule of nephron in the trunk kidney, increased significantly in 60 ppt treatment 48 hours from starting the experiment (P<0.05). The thickness of the epithelium tubule in both trunk and tail parts showed no significant differences during the adaptations (P>0.05). According to the results, histomorphological changes in the different parts of the kidney returned to the basic structure with in 24 to 48hours after exposure to different salinities.