Morphometry of the kidneys of fresh water percoid and ostariophysian teleosts.
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Kidneys of four fresh water teleost species representing percormorpha (Oreochromis niloticus and Micropterus salmoides) and Ostariophysi (Cyprinus carpio and Clarias mossambicus) were studied for quantitative structural characteristics using tissues fixed by perfusion. The renosomatic index (weight of kidney/weight of fish) was higher in the ostariophysian than percoid fish (p < 0.05) but values of volume of nephronic tissue/body weight were not significantly different. Results obtained by point counting morphometry showed that the kidneys of the percoid species were made up of 56.85-64.4% nephronic tissue, 30.45-32.47% blood vessels, 2.84-8.20% ureter and ureteral ducts and 2.07-2.48% connective tissue. The kidneys of the osariophysian species comprised of 35.27-36.71% nephronic tissue, 27.86-29.29% blood vessels, 1.59-4.20% ureter and its ducts, 29.07-29.51% interstitial cells and 2.70-3.60% connective tissue. The mean values for the volume proportions of the components of nephronic tissue were not significantly different in the percoids and ostariophysians and they were; renal corpuscles 3.84-6.54%, neck segments 0.50-1.11%, proximal segments 67.17-69.72%, distal segments 18.16-20.55%, and collecting tubule-collecting duct (CT-CD) system 5.66-7.41%. These results show that the quantitative structural characteristics of the kidneys of fresh water species from different orders are quite similar and emphasise the all persuasive influence of the environment on renal structure and function in teleosts.