Histological Structure of Liver, Trunk Kidney and Spleen of the Altai Osman Oreoleuciscus potanini (Cyprinidae) from the Isolated Population of Lake Kidelyu (Altai Republic, Russia)

For the first time, histological structure and morphometric indices of the liver, trunk kidney and spleen of the Altai osman Oreoleuciscus potanini (Kessler, 1879) are presented. The liver parenchyma has hepatocyte-sinusoidal cord-shaped structure. The biliary structures are presented by isolated and biliary-venous. The sections of the nephron of the trunk kidney (proximal and distal tubules) and collecting tubules were morphologically clearly distinguished by the area of the nucleus and the height of the epithelium, the development of the brush border (limbus strigillatus) and the thickness of the basal membrane. The spleen structure is presented by connective tissue trabeculae representing the organ stroma. Fuzzy boundaries are noticeable between the red and white pulp, the volume fraction of the white pulp (55.98%) is higher than that of the red pulp (37.82%). Pathological changes in the liver (inflammation near the bile ducts, foci of vacuolization, expansion of the liver sinusoids, foci of cells with signs of pycnosis) were insignificant, both by distribution and degree of development. In the kidneys of some individuals, localized foci of inflammation and degradation of the renal tubules were detected. In the future, the described morphological features of the histological structure of the liver, trunk kidney and spleen of the Altai osman will allow to conduct monitoring studies aimed at assessing the state of populations of endemic fish species in the reservoirs of the Altai Mountains, and to deepen the understanding of the morphology and histology of carp-like fish (Cypriniformes).