Structural changes in the kidney of freshwater mud eel Amphipnous cuchia (Ham.) subjected to different osmotic...

A histophysiological study was made of the kidney of Amphipnous cuchia subjected to different osmotic conditions (distilled water, 50% and 15% sodium chloride solution). These fish possess typical glomerular kidneys having nephrons composed of a glomerular body, neck segment, proximal convoluted segment (I & II), distal segment, and collecting duct system. When subjected to a hypotonic medium (distilled water) the fish show marked expansion in glomeruli resulting in 'glomerulitis'. A marked shrinkage in glomerular body tissue is found after 50% salt solution treatment and the fish die within one hour of immersion. Many pathological changes occur in the renal capsule and renal segment when the fish are treated with 15% salt solution. The glomerular bodies show shrinkage, degeneration and cyst formation. The glomerular shrinkage is probably due to constriction of arterioles which affects the filtration rate and thus protects against loss of water. Formation of cysts could be a protective device to save the glomeruli from degeneration. The renal tubules show hypertrophy, vacuolization, nuclear degeneration and cyst formation.