Study of kidney anatomy and microscopic of renal proximal and distal tubules of middle and posterior part of kidney tissue in Oncorhynchus mykiss and Astronotus ocellatus

The present study was conducted to compare the histology of renal proximal tubules (I) and (II) in two species (Rainbow trout and Oscar). Rainbow trout, known as Oncorhynchus mykiss scientific name from the Salmonidae family which is cultivated and freshwater. Oscar fish, the scientific name is Astronotus Ocellatus, which is one of the most well-known ornamental fish of the Chichlidae family. Five piece of the two fish species were selected randomly and their macroscopic specification and morphometric measurements were recorded. Samples were fixed in %10 formalin buffer and the cuts were prepared with a thickness of five micron and then they were stained by Hematoxylin and eosin and Periodic acid–Schiff method and studied by light microscopy. The data were analyzed with SPSS software and T-Test statistical test (P <0.05). Proximal and distal tubes were detected and the variables were measured. The size of the cell nucleus and the outer diameter of the proximal (I) had a significant difference (P<0.01). There has been significant difference in the number and the size of cell and its nucleus, the inner and outer diameter of the proximal II between two species (P<0.001). The number, cell size of the distal tubules has been significant difference between two species (P<0.01). The size of the cell nucleus, the inner and outer diameter of the distal tubules have been significant difference between two species (P<0.001). According to the results, the anatomy and histology of kidney tissue are different in the Rainbow trout and Oscar fish.