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Immunohistochemical localizations of horseradish peroxidase (HRP) and cathepsins B and H in the lysosomal system of the rat kidney proximal tubule cells were investigated during the internalization and degradation of HRP by these cells. At fixed intervals after intravenous injection of HRP, the kidneys were fixed by perfusion. Five to fifteen minutes after this injection, endocytosed HRP was detected in fine granules beneath the brush border. Thirty minutes later, it accumulated into large aggregates of granules (phagosomes), where both enzymatic and antigenic activities appeared to cause HRP to be lost rapidly. After 1 hour, the aggregates of phagosomes increased in number and size but soon began to decrease gradually. In the early stage, cathepsins B and H were not detected in the apical cytoplasmic granules. However, they were present in the lysosomal compartments, together with the HRP. The large aggregates of phagosomes showed a patchy reaction, especially approximately 30 minutes after injection, whereas other medium-sized phagosomes were stained heavily. Aggregates of phagosomes were present only in the S1 segment. These results suggest strongly that cathepsins B and H are involved in the cellular degradation of endocytosed HRP.
Anat Rec 1988 Aug
PMID:Involvement of cathepsins B and H in lysosomal degradation of horseradish peroxidase endocytosed by the proximal tubule cells of the rat kidney: I. Histochemical and immunohistochemical studies. 318 72

A protein of approximately 28,000 relative molecular mass (Mr) cross-reacting with antiserum against the 28,000-Mr rat renal calcium-binding protein (calbindin-D28k) has been localized in the kidney of a salientian amphibian, Rana catesbeiana. Cells reactive for calbindin-D28k were found in the distal tubule at all stages of metamorphosis by the unlabeled antibody peroxidase-antiperoxidase technique. Adult kidneys appeared to have more calbindin-D28k-positive cells. The renal corpuscle, neck, and proximal tubule were negative. An immunoreactive 28,000-Mr band that comigrated with the band of calbindin-D28k was visualized by the immunoblot technique. The finding of the 28,000-Mr calbindin-D in the anamniotic kidney demonstrates that this calcium-binding protein (CaBP) is phylogenetically older than our previous studies of higher vertebrates had revealed (Rhoten et al., 1985). Although the function of calbindin-D28k in the distal nephron is unknown, this CaBP can now be presumed to have functional significance in the mesonephric as well as the metanephric kidney.
Anat Rec 1986 Oct
PMID:Calcium-binding protein (28,000 Mr calbindin-D28k) in kidneys of the bullfrog Rana catesbeiana during metamorphosis. 349 Aug 5

The 40-minute infusion of norepinephrine (NE) into the renal artery of dogs produces a reversible ischemic model of acute renal failure. While the physiology of this model has been extensively studied, no complete description of the pathology exists. This study uses light microscopy and transmission electron microscopy to describe and quantitate the structural and ultrastructural changes which occur in the kidneys of dogs 1, 3, and 24 hours after the intrarenal infusion of 0.75 mg/kg/minute of NE. One hour after a 40-minute NE infusion the majority of convoluted and straight proximal tubules showed apical blebs, loss of brush border, microvillar whorl formation, and mitochondrial condensation and high-amplitude swelling with flocculent densities. Necrotic cells were occasionally seen at 1 hour. The injury was progressive after 3 hours and by 24 hours animals had either complete or partial patchy necrosis of all regions of the proximal tubule. The percentages of injured and necrotic proximal tubules in outer, mid-, and inner cortical regions are presented. We conclude that the extent and pattern of injury seen after NE infusion differs significantly from the renal artery clamping model of ischemia.
Anat Rec 1986 Apr
PMID:Morphology of norepinephrine-induced acute renal failure in the dog. 370 79

The kidneys from 6 domestic fowl were fixed in situ by perfusion from the left ventricle. In the bird there are two types of nephrons. One reptilian-type without Henle's loop and medullary tissue, and one mammalian-type with Henle's loop lying in medullary tissue. Serial sections from kidney tissue embedded in plexiglass or in paraffin were used to study the architecture of eight reconstructed reptilian-type nephrons from different cortical levels. All reconstructed nephrons had four major bends, but particularly in the subcapsular nephrons additional bends parallel to the kidney surface were found. There was no loop of Henle, but before entering the collecting duct the distal tubule usually had a very thin-walled segment. No proximal convoluted part was found in the reptilian-type nephrons. The length of the tubules varied between 3,000 microns and 6,000 microns. In the distal tubule a macula densa segment was found in all nephrons of the reptilian and mammalian type. The capillary network between the inter- and intralobular veins was composed of increasingly larger capillaries towards the intralobular vein. Segments of the distal tubule were indented into these capillaries and completely surrounded by them. In the nephrons of the mammalian type the proximal tubule was found to be convoluted as is usual for mammalian species.
Anat Rec 1985 May
PMID:Structure of the avian kidney. 407 41

The presence of carbonic anhydrase activity in rabbit and mouse kidneys was examined using a histochemical procedure with plastic embedded sections stained by the modified version of the cobalt-phosphate method (Hansson, 1967, 1968; Ridderstrale, 1976). Proximal convoluted tubules (S1 and S2 segments) in both species were strongly positive for carbonic anhydrase activity on the membranes of the luminal, lateral, and basal surfaces. The apical cytoplasm beneath the brush border and the nuclei also stained positively for carbonic anhydrase. The S3 segment (pars recta) of the proximal tubule in the rabbit was positive on the luminal membrane, with somewhat less intensity seen on the lateral and basal surfaces. This segment in the mouse was completely negative. The first part of the thin limbs of long-looped nephrons exhibited strong staining in the mouse. Faint luminal staining was present on descending thin limbs of short-looped nephrons in the mouse. In the rabbit, both the medullary and cortical ascending thick segments of the limb of Henle were completely negative. In contrast, the medullary and cortical ascending thick limbs in the mouse kidney showed staining on all plasma membranes. The intercalated cells in the cortical and medullary portion of the collecting tubules stained positively for carbonic anhydrase in both species. The principal cells of the collecting duct in the cortex were negative in the rabbit and faintly positive in the mouse. The principal cells in the upper medullary collecting tubules in both species stained intensely along the luminal, lateral, and basal cell membranes. The papillary collecting ducts were largely negative in both the rabbit and the mouse. Some interstitial cells in the rabbit in the region of the papillary tip were strongly positive. We conclude that there is a marked difference in carbonic anhydrase activity within and between the renal tubular segments of the rabbit and the mouse. In addition, these distinct differences that exist between the two species correlated with known physiological roles in ion transport.
Anat Rec 1982 Nov
PMID:Carbonic anhydrase histochemistry in rabbit and mouse kidneys. 681 76

Five months following unilateral nephrectomy, the parietal epithelia in the remaining kidneys of Sprague-Dawley rats were examined by light and electron microscopy. Compared with controls, the kidneys from uninephrectomized rats exhibited a dramatic increase in mass characteristic of compensatory hypertrophy. Approximately 20% of the renal corpuscles in the hypertrophied kidneys had parietal epithelia lined by tall cells which possessed a brush border and other morphological characteristics of proximal tubule cells. In some instances proximal tubulelike cells made up over half of the cells lining the parietal epithelium. The possible significance of this finding is discussed.
Anat Rec 1981 May
PMID:The presence of proximal tubulelike cells in the kidney parietal epithelium in response to unilateral nephrectomy. 725 94

The ultrastructure of renal tubule cells was studied in the European lesser spotted dogfish by the evaluation of thin sections and freeze fracture replicas. Computer-assisted three-dimensional reconstruction of entire nephrons was performed. The distinction of nephron segments and collecting tubule was made using results of previous histological work. The first proximal tubule segment (PI) consists of two subsequent portions, PIa and PIb. PIa is a component of the lateral countercurrent bundle, and PIb, which displays an apical tubulovesicular apparatus and an extended lysosomal compartment, is located in the vicinity of the glomeruli. Rod-shaped intramembrane particles were detected in PIa. The second proximal tubule segment (PII) is a special segment in elasmobranch and teleost fish. PII differs largely from PI in cell morphology and function. The apical cytoplasm was filled with small clear vesicles, and an apical endocytic apparatus was lacking. In the apical cell membrane, rod-shaped particles were revealed by freeze fracture. The apical tight junctions of PI and PII consisted of seven to ten meandering strands. The distal nephron was subdivided into two major segments: early distal tubule (EDT) in the lateral countercurrent bundles and late distal tubule (LDT) in the mesial tissue. The EDT showed marked amplification of basolateral cell membranes. The tight junctions displayed a low number of continuous parallel strands, which is also characteristically found in the diluting segments of other vertebrates. LDT cells showed cytoplasmic studs and rod-shaped intramembraneous particles at the apical cell membrane, thereby resembling type A intercalated cells of collecting duct. The collecting tubule (CT) emerged from the LDT and was part of the countercurrent arrangement inside the lateral bundles. Tight junctions of LDT and CT consisted of many meandering strands in a honeycomb pattern. With immunohistochemistry, binding sites of a polyclonal antibody against an extraplasmic portion of rat gastric H(+)-K(+)-adenosine triphosphatase (ATPase) were observed at the apical cell membrane of PIa, PII, and LDT. From the colocalization of binding sites for the antibody against the transport enzyme with rod-shaped intramembrane particles, we assume that these might be the morphological correlate of gastric H(+)-K(+)-ATPase-like enzyme in the renal tubule.
Anat Rec 1993 Apr
PMID:Renal tubule of dogfish, Scyliorhinus caniculus: a comprehensive study of structure with emphasis on intramembrane particles and immunoreactivity for H(+)-K(+)-adenosine triphosphatase. 838 22

Rodent models of polycystic kidney disease (PKD) have provided valuable insight into the cellular changes associated with cystogenesis in humans. The present study characterizes the morphology of renal and extrarenal pathology of autosomal recessive PKD induced by the wpk gene in Wistar rats. In wpk(-/-) rats, proximal tubule and collecting duct cysts develop in utero and eventually consume the kidney. Increased apoptosis, mitosis, and extracellular tenascin deposition parallel cyst development. Extrarenal pathology occurs in the immune system (thymic and splenic hypoplasia) and central nervous system (CNS; hypoplasia to agenesis of the corpus callosum with severe hydrocephalus). Severity of hydrocephalus varied inversely with size of the corpus callosum. In wpk(-/-) rats, the corpus callosum exhibits relatively few axons that cross the midline. This CNS pathology is similar to that described in three human renal cystic syndromes: orofaciodigital, genitopatellar, and cerebrorenal-digital syndromes. Collecting duct and ventricular ependymal cilia appear morphologically normal. To determine if rodent background strain and the presence of modifier genes affect severity of the disease, we crossed the Wistar-wpk rat with Brown Norway (BN) and Long Evan (LE) rats and found the degree of renal and cerebral pathology was diminished as evidenced by lower kidney weight as a percent of body weight and serum urea nitrogen concentration in cystic rats on LE or BN strains as well as less prominent cranial enlargement. Crosses with BN rats allowed us to localize the wpk gene on chromosome 5 very close to the D5Rat73 marker. The wpk gene lies within a chromosomal region known to harbor a PKD modifier locus. In summary, the types of renal and cerebral pathology seen in the Wistar wpk rat are a unique combination seen only in this rodent model.
Anat Rec A Discov Mol Cell Evol Biol 2004 Apr
PMID:Development of multiorgan pathology in the wpk rat model of polycystic kidney disease. 1505 65

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.
Anat Rec A Discov Mol Cell Evol Biol 2006 Jun
PMID:Microanatomy and ultrastructure of the kidney of the African lungfish Protopterus dolloi. 1670 93

Here we present a detailed morphological description of the alligator (Alligator mississippiensis) kidney and nephron. We present a series of histological, histochemical, and immunohistochemical markers that clearly define the seven regions of the alligator nephron. The alligator kidney is composed of many paired (mirrored) lobules on each kidney (lobe). Single nephrons span the width of lobules three times. The fine structure of glomeruli, lying in rows spanning the height of the lobule, is resolved by periodic acid methionine silver (PAMS) and periodic acid Schiff's (PAS) histochemistry. Glomeruli are connected to the proximal tubule (PT) via a neck segment. The PT is alcian blue-negative, making it distinct from the distal tubule (DT), connecting segment (CS), and collecting duct (CD). The PT is clearly identifiable by a PAS-positive brush border membrane. The PT is connected to the DT via an intermediate segment (IS) that makes a 180 degrees turn to connect these tubules. PAMS-positive material is found in the lumens of the PT, IS, and DT. Also, PAMS-positive granules are found in the DT, CS, and CD. Immunolocalization of the Na(+), K(+)-ATPase to the basolateral membrane of the DT, CS, and CD suggests a role of this enzyme in driving primary and secondary transport processes in these segments, including bicarbonate transport into the lumen of the DT (leading to an alkaline urine). Through the techniques described here, we have identified a series of distinct markers to be used by pathologists, veterinarians, and researchers to easily identify alligator nephron segments. Anat Rec, 2009. (c) 2009 Wiley-Liss, Inc.
Anat Rec (Hoboken) 2009 Oct
PMID:Morphology and histochemistry of juvenile American alligator (Alligator mississippiensis) nephrons. 1968 9


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