The structural and ultrastructural organization of the cellular constituents of the trunk kidney of grass carp (Ctenopharyngodon idella)

Abstract

The trunk kidney of grass carp mainly consisted of renal tubules with a few interstitial hematopoietic tissues. The component structure of fish nephron markedly varies between different species of fish. The nephron of grass carp consisted of morphologically distinct segments; renal corpuscles, neck segment, proximal, intermediate, distal, and collecting tubules. The glomerulus of renal corpuscles mainly composed of mesangial cells and well‐developed podocytes that extended their processes to the endothelium of glomerular capillaries forming the filtration barrier. The podocytes expressed both α‐SMA and the transforming growth factor gene, TGF‐β. The proximal convoluted tubules (PCTs) expressed α‐SMA iNOS2, and TGF‐β. The cytoplasm of PCT was rich in mitochondria and rER, in addition to the presence of well‐developed basolateral tubular system and apical brush borders. Collecting tubules distributed throughout the kidney and lined by principal and flask cells. The interstitial hemopoietic tissues contained iNOS2‐positive polymorphic granulocytes, CD3‐positive T lymphocytes, rodlet cells, dendritic cells, macrophages, melanomacrophage centers, and telocytes. This study described for the first time the cellular components of the nephron and its associated hemopoietic tissues that can act as a basis for studying the structural changes that may occur in the kidney of grass carp during water salinitiy, environmental, or experimental conditions.

New Data on Nephron Microanatomy and Ultrastructure of Senegal Bichir (Polypterus senegalus)

“…Histological analysis has shown that the bichir renal corpuscle has the same structure as both lungfish and freshwater teleosts and amphibians [ 12 , 13 , 14 , 15 ]. It has been established that the cut diameter of the renal corpuscle increases in the series P. senegalus —freshwater bony fish Ctenopharyngodon idella ; Channa punctatus —amphibians Rana cancrivora; Triturus (Cynops) pyrrhogaster [ 13 , 15 , 16 ].…”

“…It should be noted that the outer diameter of the tubules increases in the series P. senegalus —freshwater bony fish C. idella , C. punctatus —lungfish Protopterus dolloi—amphibians R. cancrivora, T. (Cynops) pyrrhogaster [ 12 , 13 , 15 , 16 ]. It is known that the outer diameter of the tubules depends both on the lumen of the tubules and on the height of the epitheliocytes that form the tubules.…”

“…It is known that the outer diameter of the tubules depends both on the lumen of the tubules and on the height of the epitheliocytes that form the tubules. The height of nephron epithelial cells increases in the following order: P. senegalus —freshwater bony fish— C. punctatus , Coregonus migratorius—lungfish P. dolloi —amphibian Bufo bufo [ 15 , 17 , 18 , 19 ].…”

“…The proximal tubules are an essential part of the nephron in all groups of cyclostomes, fish, and amphibians. In bichir, as well as in the lungfish P. dolloi , freshwater bony fish, and amphibians, they are represented by two types of cells with a common structural plan [ 13 , 14 , 15 , 19 , 21 , 26 , 32 ]. Thus, the presence of a developed mechanism of reabsorption in the proximal tubule of the nephron was formed at the early stages of the evolution of lower vertebrates, which affected the conservatism of this part of the nephron, regardless of the environmental conditions of fish and amphibians.…”

Structure of the Eurasian moorhen spleen: A comprehensive study using gross anatomy, light, and transmission electron microscopy

“…The sections were examined and photographed using a JEM −2,100 transmission electron microscope (JEOL Ltd., Tokyo, Japan). Whenever needed, the Adobe Photoshop CS6 software was used to enhance the visual contrast of the electron micrographs (Mokhtar, 2020; Soliman, Kamal, & Abd‐Elhafeez, 2019).…”