Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Dipnoi (lungfishes) have developed true lungs, having the ability to take oxygen from both the gills and the lungs. During the tropical dry season, many lungfish estivate on land, breathing only air. The estivation period is accompanied by profound functional modifications, including the suppression of urine. Thus, the lungfish kidney must be designed to cope with these dramatic cyclic changes in renal function. We study here the microanatomy and the structure of the kidney of the African lungfish Protopterus dolloi, maintained under controlled freshwater conditions. Chemical microdissection, light microscopy, and scanning and transmission electron microscopy have been used. The nephrons of P. dolloi are composed of a renal corpuscle (RC) and of a renal tubule that appears divided into five morphologically distinct segments: neck segment (NS), proximal tubule (PT), intermediate segment (IS), distal tubule (DT), and collecting tubule (CT). Paired CTs abut into a collecting duct, the latter emptying into an archinephric duct. The RCs lie in the mid-zone of the kidney, between the PTs and the convoluted DTs. The spatial distribution of these elements allows recognition of a kidney zonation. The RCs group into clusters (3-4 RCs per cluster) that are supplied by a single arteriole surrounded by pericytes. Each cluster appears to represent a functional unit with a common hemodynamic regulatory mechanism. The major processes of the podocytes form flattened networks that appear to constitute an integrated system due to the presence of gap junctions. The existence of mesangial cells with large cell processes, and of mesangial cells with a dendritic appearance, suggests a complex functional role (contractile and phagocytic) for the mesangium. The NS and the IS are the narrowest nephron segments, formed only by multiciliated cells. The PT and the DT can be subdivided, based on the tubular morphology and on cell composition, into portions I and II: PTI is formed only by brush border (BB) cells, while PTII contains BB and multiciliated cells. The DTI is formed by segment-specific cells, while the DTII contains segment-specific and a small number of flask cells. The CT contains principal and flask cells in a 5:1 ratio. The flask cells adopt two different configurations (with a narrow canaliculus or with a large cavity). The main goal of this study was to disclose specific kidney features that could be related to function, phylogeny, and habitat. In addition, the present results constitute the basis for a study of the morphologic changes that should occur in the kidney of P. dolloi during estivation.
 ...
PMID:Microanatomy and ultrastructure of the kidney of the African lungfish Protopterus dolloi. 1670 93

The structure of the nephron in adult soft-shelled turtles (Pelodiscus sinensis) was studied by light microscopy, transmission and scanning electron microscopy. The kidney contained 5-6 renal lobes. Nephrons of P. sinensis are composed of a renal corpuscle (RC) and of a renal tubule that appears divided morphologically into five distinct segments: neck segment (NS) (This segment is only present in approximately 10% of the nephrons), proximal tubule (PT), intermediate segment (IS), distal tubule (DT), and collecting duct (CD). The RCs and most of the convoluted DTs lie in the central zone, while the PTs and the CDs lie in the peripheral zone of the renal lobe. The renal corpuscle is relatively large with especial processes in podocytes and a thick basement membrane. The podocyte processes covering a large capillary area can be observed by TEM, and the major podocyte processes formed a very specific pattern in SEM. The podocyte processes expand to form a flattened network over the whole capillary loops surface, and only may observe little filtration slits in glomerular area. The neck segment when presentis short and has a relatively narrow lumen, consisting of cuboidal or squamous cells. There is a well-developed endocytic-lysosomal apparatus in the apical cytoplasm of the PT. The proximal tubule and intermediate segment cells show some differences between male and female. It showed that proximal tubule cells of male soft-shelt turtle contain lateral intercellular spaces, into which extensions of the cell membrane protrude, and the basal cell membrane forms a conspicuous labyrinth. Whereas, the basal and lateral cell membranes of the female are smooth, and no later-basal intercellular spaces. The differences between male and female in the middle segment cells is similar to proximal tubule cells. Not previously reported in vertebrate kidneys. The IS is the narrowest nephron segment, formed by multiciliated as well as nonciliated cells. In DT cells, basolateral interdigitations and infoldings are particularly well-developed. The CD contains clear cells with numerous secretory granules and dark cells with dense mitochondria and an elaborate Golgi complex. This study was undertaken in order to disclose specific kidney features in P. sinensis that could be related to function. In addition, the ultrastructure of the nephrons in P. sinensis are discussed in relation to other turtles and vertebrates.
 ...
PMID:Ultrastructure of the nephron in the soft-shelled turtle, Pelodiscus sinensis (Reptilia, Chelonia, Trionychidae). 2312 84