[Cytologic and ultrastructural organization of the kidney tubules of certain amphibia].

As the investigation performed demonstrated, there is no principle differences in cytological organization in kidneys of five species of Amphibia whose mode of life to a certain extent is connected with water environment. Nevertheless, in different species epithelium of proximal parts of nephrons demonstrates various intensity of apocrinic secretion. Granules situating in the supranuclear zone of the epithelial cells of these parts are, in fact, autophagic lysosomes, their function is evidently connected with both lysis of the absorbed proteins and with autolysis of the apical cellular part in the process of secretion. The epithelial cytoplasm in the distal part of the nephron is characterized by a high succinate dehydrogenase activity; it is connected with its main function--osmoregulation. There are dark and light cells, resembling those in higher vertebrates, in the connecting part and in the collecting tubes. Ultrastructural organization of the brown frog nephron cells has much in common with that of epithelium of the secondary kidney urinary canaliculi.