Metaplasia of the parietal layer of Bowman's capsule in the human kidney: incidence in alcoholic liver disease and hypertension

This report is the second of two surveys to determine the incidence of metaplasia of Bowman's parietal epithelium in the human kidney. Human kidney sections obtained at autopsy at the Department of Pathology, University of Texas Medical Branch, Galveston, Texas, were examined with the light microscope. The kidneys were fixed in neutral formalin, sectioned at 6 microns and stained with hematoxylin and eosin. Autopsy records were consulted after kidney section examination to determine if there was any correlation between clinical disease, histopathological changes in organ systems and metaplasia of Bowman's capsule. The kidney sections represented both sexes in 8 age groups, from less than one year to 80 years. A total of 174 kidneys, representing 174 individuals, were evaluated. One hundred renal corpuscles were counted per section and the parietal layer of Bowman's capsule was classified as normal (squamous) or metaplastic (cuboidal). Of the 174 kidneys examined, 137 (79%)--79 male and 58 female--had metaplasia of Bowman's capsule. On the average, in the kidneys with the lesion, 6% of the renal corpuscles had metaplasia of Bowman's parietal layer. The lesion was present in both sexes in all age groups. The autopsy records revealed that metaplasia of Bowman's parietal epithelium was usually present with hepatic fatty changes and/or congestion. Alcoholic liver disease and hypertension represented the most frequent clinical diseases in the sample; these conditions had the highest incidence of metaplasia. Twenty-six of the 174 kidney samples were from individuals with alcoholic liver disease, all of whom had metaplasia of Bowman's capsule.(ABSTRACT TRUNCATED AT 250 WORDS)     

Distribution of actin bundles in Bowman's capsule of rat kidney

In this study we define the distribution of actin bundle arrangement in Bowman's capsule of rat renal corpuscles. Parietal cells of Bowman's capsule were examined by conventional light microscopy, electron microscopy and confocal microscopy. Within each parietal cell individual actin bundles are arranged in a parallel fashion running the length of the cell. Computer reconstructions obtained using confocal microscopy clearly show the lengths of actin bundles to be arranged, on a capsule level, end-to-end, at angles and perpendicular to bundles in adjacent cells. The bundles stain positively for non-muscle myosin and vinculin. The presence and arrangement of actin bundles in parietal cells is consistent with a role in reinforcing capsule structure.     

Spontaneous tubular (cuboidal) metaplasia of the parietal layer of Bowman's capsule in Cynomolgus monkeys (Macaca fascicularis)

Tubular (cuboidal) metaplasia of the parietal epithelium of Bowman's capsule was observed in 19 (10 males, 9 females) of 56 adult control Cynomolgus monkeys. Cuboidal epithelium replaced the normally present flattened epithelium to various degrees in animals affected. Cuboidal cells revealed an eosinophilic cytoplasm and vesicular nuclei, thus resembling proximal convoluted epithelial cells in all respects. Continuity of the cuboidal glomerular epithelium with that of the proximal tubule was occasionally observed.     

THE COLUMNAR CELLS OCCURRING IN THE PARIETAL LAYER OF BOWMAN''S CAPSULE : Cellular Fine Structure and Protein Transport

The renal corpuscles of adult, C3H Swiss, male mice contain testosterone-sensitive, columnar cells in the parietal layer of Bowman's capsule. A study of the normal fine structure of these cells reveals several distinctive characteristics: a microvillous brush border; apical tubular invaginations and apical tubules; an elaborate infolding of the basal surface membrane forming cellular compartments, which contain numerous mitochondria; and a complex group of membrane-limited cytoplasmic inclusions. This appearance is remarkably similar to the fine structure of cells in the proximal convoluted tubule. 1 hr after an in vivo injection of horseradish peroxidase, numerous protein-absorption droplets occur in the columnar cell cytoplasm. The speed and cytomorphology of protein transport by these capsular cells closely resemble the handling of peroxidase by the proximal convoluted tubule. Origins for these testosterone-sensitive cells are discussed briefly. Morphological evidence is presented for the differentiation of squamous cells in Bowman's parietal capsule into columnar cells, which appear structurally and functionally identical with proximal convoluted tubular epithelium.     

Enzymatic histochemistry of mouse kidney in plastic

Two-micrometer sections of methacrylate-embedded kidney were used to investigate the enzymatic activities of mouse kidney where the proximal tubule and Bowman's capsule from the same corpuscle were viewed in the same section. Alkaline phosphatase, acid phosphatase, 5'-nucleotidase, gamma-glutamyl transpeptidase, N-acetyl-beta-glucosaminidase, leucine aminopeptidase, alpha-naphthyl butyrate esterase, and adenosine triphosphatase activities were observed in the proximal tubule, but only 5'-nucleotidase, alpha-naphthyl butyrate esterase, and alkaline phosphatase were observed in the squamous portion of the parietal epithelium of Bowman's capsule. The use of methacrylate-embedded tissue allowed more precise localization of enzymatic activity than is possible with most frozen sections. This may provide interesting applications not only for characterization of kidney diseases but also for characterization of other normal and abnormal tissues.     

Pericapsular smooth muscle cells in renal corpuscles of the Mongolian gerbil

Summary During the course of a systematic investigation of the renal corpuscles in various desert rodents (Meriones unguiculati, Meriones shawii, Psammomys obesus, and Dipodymis), a thickened Bowman's capsule was observed light microscopically in some kidneys of adult Meriones unguiculati (Mongolian gerbil). Electron microscopic studies show that this unusual finding may depend on the presence of one or two layers of typical smooth muscle cells adjacent to the outer surface of the basal lamina. In the kidneys of other species of desert rats examined, no pericapsular smooth muscle cells were observed.     

泰和鸡肾小球旁器的观察

本文用光镜和透射电镜对泰和鸡(乌骨鸡)的肾小球旁器进行了观察。结果表明,泰和鸡的肾小球旁器由球旁细胞、过渡型致密斑、球外间膜细胞和极周细胞所组成。极周细胞在鸟类还属首次报道,它位于肾小囊脏层与壁层上皮移行处,环绕着肾小体的血管极,其结构与哺乳动物的相似。本文还就泰和鸡肾小球旁器的结构与功能的关系作了讨论。     

Alkaline phosphatase activity at unusual sites of human foetal kidney

Summary Frozen sections of human foetal kidneys were treated by the lead citrate method in order to demonstrate alkaline phosphatase (ALP) activity. Unexpectedly, ALP activity was observed over the parietal layer of Bowman's capsule, in addition to usual localization in proximal tubules and blood vessels. The enzyme was confined to the membrane of microvilli belonging to tall columnar cells. Normally, in the mature nephron, these high cells are absent from the parietal layer that is instead entirely composed of squamous epithelium.ALP activity was also revealed at another unusual site in the kidney medulla. A collar of mesenchymal cells encapsulating groups of tubules and calyces gave an intense enzymatic reaction. The activity was present over the membrane of long cytoplasmic processes. The cytoplasm showed a well developed rough endoplasmic reticulum, an indication of a high rate of protein synthesis. The nearby presence of numerous collagenous fibrils is concordant with this assumption. Moreover, these ALP-positive cells might represent an intermediary stage through which cells have to pass before differentiating.     

The ultrastructure of the renal corpuscle of a lizard

The few and small renal corpuscles of the lizard Podarcis (= Lacerta) taurica are composed of a tuft of three to four capillaries (glomerulus), Bowman's capsule and mesangium. The thin interdigitated capillary endothelial cells are, in most regions, in contact with the mesangium. In some regions, however, they rest on a bilaminate basement membrane with an electron-dense lamina densa and a less dense lamina rara. Bowman's capsule is composed of visceral and parietal layers. The epithelial cells (podocytes) of the visceral layer bear trabeculae connected to pedicels with microvilli. The pedicels rest on a bilaminate basement membrane which in some regions has a double-layered densa with connecting bands. Generally, this basement membrane is thicker than that of the capillary endothelial cells. The mesangium is composed mostly of irregular satellite cells with large nuclei and cytoplasmic processes, but also has smaller cells with kidney-shaped nuclei and cytoplasmic processes containing microfilaments. The mesangium cells are embedded in a collagenous matrix which extends to invade the area between the epithelial basement membrane and the capillary endothelium. These observations are discussed in relation to the structure and function of vertebrate renal corpuscles with special reference to the mesangium.     

Discrimination of various epithelia by simple morphometric evaluation of the basal cell layer. A light microscopic analysis of pseudostratified, metaplastic and dysplastic nasal epithelium in nickel workers

This study presents a simple morphometric method for objective classification of pseudostratified, various types of metaplastic, and dysplastic epithelium by evaluation of cellular features in the basal layer only. Fifty-four biopsy specimens were taken for diagnostic reasons from the nasal mucosa of nickel workers, and semithin toluidine-blue-stained sections were analysed. The most sensitive parameters in distinguishing between the various types of epithelium were: (i) the transverse nuclear diameter, (ii) the size of the nucleoli and (iii) the basal cell width expressed as an index weighted towards the cell profiles with the broadest attachment face on the basal lamina. A combination of these three parameters allows a clear separation between dysplastic, metaplastic and pseudostratified epithelium. The sequential increase in these parameters from pseudostratified epithelium through two histologically distinguishable stages of metaplasia (stratified cuboidal and mixed stratified cuboidal/stratified squamous epithelium) to fully developed squamous epithelium supports the concept that metaplasia develops gradually. The continuous increase in these parameters from metaplasia to dysplasia further suggests that metaplasia is a necessary step in the development of nasal epithelial dysplasia. This morphometric model appears especially useful in monitoring small sequential epithelial changes, and might also be used for evaluating other types of epithelia.     

Morphology of the kidney of adult bowfin, Amia calva, with emphasis on "renal chloride cells" in the tubule

The nephron of adult bowfin, Amia calva, was described using light and electron microscopic techniques. The kidney of the bowfin possesses an abundant supply of renal corpuscles with each consisting of a glomerulus and a Bowman's capsule of visceral (podocyte) and parietal layers. No juxtaglomerular apparatus is present. The epithelium of the tubule is continuous with the parietal epithelium and is divisible in descending order into neck, first proximal, second proximal, first distal, second distal, and collecting segments. The tubules drain into a complex system of collecting ducts that ultimately unite with the main excretory duct, the archinephric duct. Mucous cells are the dominant cell throughout the entire ductular system. Nephrostomes are dispersed along the kidney capsule. The neck segment has a ciliated epithelium, and while both proximal segments possess a prominent brush border, the fine structure of the first implies involvement in protein absorption and the second in the transport and reabsorption of solutes. The cells of the first distal segment are characterized by deep infolding of the plasma membrane and a rich supply of mitochondria suggesting the presence of a mechanism for ion transport. The second distal segment is composed of cells resembling the chloride cells of fishes and these cells are present in progressively decreasing numbers in the collecting segment and duct system so that only a few are present in the epithelium of the archinephric duct. The "renal chloride cells" possess an abundant network of smooth tubules and numerous mitochondria with a rich supply of cristae. Glycogen is also a conspicuous component of these cells. The presence of "renal chloride cells" in this freshwater holostean, in other relatively primitive freshwater teleosts, and in larval and adult lampreys is discussed with reference to both phylogeny and the need for a special mechanism for renal ion conservation through absorption.     

Cytochemical correlates of structural sexual dimorphism in glandular tissues of the mouse. I. Studies of the renal glomerular capsule.

The parietal epithelium of Bowman's capsule has been analyzed by enzyme cytochemistry in kidneys of mice (C57BL/6J) from birth to 50 days of age. There is a greater tendency for cells in the central portions of the capsular crescent to be cuboidal in post-pubertal males than in pre-pubertal mice of either sex or in post-pubertal females where they are generally squamous; moreover, these heightened capsular cells have a distinct microvillous border. Cytochemical procedures were selected which might confirm the morphological suggestion that the cuboidal parietal epithelium possesses an absorptive capacity. The oxidoreductase activity of the mitochondria of the cuboidal cells of this layer is comparable to that of the columnar cells of the proximal convoluted tubule. The cytochrome oxidase activity of the mitochondria in both of these segments of the nephron is intense. This is in sharp contrast to the unreactive mitochondria in the squamous cells of the parietal epithelium. Furthermore, a striking heterogeneity in the degree of cytochrome oxidase activity is evident in the mitochondria of the cuboidal parietal cells as well as in the cells of the proximal tubules. In the former cells, active mitochondria were generally found near microvilli at the apical ends and in the areas of the basal infoldings whereas those in a central position were more frequently unreactive. The brush border of the cuboidal capsular epithelium had prominent alkaline phosphatase and aminopeptidase activities as has previously been observed in other brush borders. Functional capacity corresponding to the morphological and cytochemical specialization of the cuboidal capsular cells was demonstrated by their uptake of horseradish peroxidase. This exogenous protein tracer could be seen in apical vacuoles and phagosomes in the cuboidal parietal epithelium. The cytochemical resemblance of the cells of this epithelium to those of the proximal convoluted tubules suggests a similar involvement in resorption and perhaps in active transport. A possible relationship of this differentiation of the capsular epithelium to the proteinuria normal for adult male mice is discussed.     

Sex difference and fine structure on epithelium cells of Bowman's capsule in mice (author's transl)

Bowman's capsules with cuboidal epithelium were found in 87.2%, 95.5%, 75.4%, 96.7%, 98.8% and 91.2% in the kidney of adult male C57BL/6J-ob, JCL-ICR, dd, E1, ASK and KK mice, respectively, while in 57.9%, 6.7%, 7.0%, 2.8% and 9.1% in adult female C57BL/6J-ob, JCL-ICR, dd, E1 and ASK mice, respectively. The renal corpuscles with cuboidal epithelium in Bowman's capsules of male JCL-ICR mice increased gradually in number from 5 to 10 weeks age. The surface of cuboidal epithelium cells was shown to have long cilia and dense microvilli, which were similar to those seen in proximal uriniferous tubules.     

TCDD alters the extracellular matrix and basal lamina of the fetal mouse kidney

The teratogenic effects of the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have previously been studied in several species, and hydronephrosis has been reported to be a frequent abnormality in near-term fetuses. C57BL/6N female mice, given 12 micrograms/kg TCDD, P.O., on day 10 of gestation were killed on days 14, 15, and 16; fetal kidneys were collected and prepared for either immunofluorescent localization of several extracellular matrix components (ECM) or transmission electron microscopy (TEM). The TCDD-treated and control kidneys showed the same pattern of staining for fibronectin, but TCDD-treated kidneys displayed a diminished overall intensity. The intensity of laminin and type IV collagen immunofluorescence also appeared to be decreased, and deviations in the pattern of antibody binding were detected for differentiating TCDD-treated nephrons. Binding of the laminin antibody to the basal lamina was decreased in the parietal layer of Bowman's capsules in more advanced stages of differentiation. TEM analysis focused on the basal lamina of the tubules and Bowman's capsule. In TCDD-exposed kidneys, ECM components adjacent to differentiating nephrons were less abundant, and the basal lamina of the developing Bowman's capsules had a diminished lamina densa. The earliest nephrons to develop display these defects and comprise the first functional filtration units of the metanephric kidney. These ultrastructural changes noted in TCDD-exposed nephrons may promote proteinuria, a condition normally observed in the developing kidney when the filtration barrier is immature.     

Cell junctions in the epithelium of Bowman's capsule

Summary The intercellular connections between the epithelial cells of Bowman's capsule were investigated. It could be demonstrated that typical zonulae occludentes (tight junctions) are present in the species (rat, hamster, and Tupaia) studied. Freeze-fracturing shows a network of anastomizing strands; some species variations are described. In the rat two strands are common. In the golden hamster mostly two to four and occasionally five strands occur. In Tupaia regularly three tight junction strands are found and also gap junctions associated with the zonulae occludentes. In thin sections the goniometric analysis confirms the freeze-fracturing results and reveals attachment zones of macular shape, which are classified as intermediate junctions and desmosomes. The functional role of these cell junctions observed in the epithelium of Bowman's capsule is discussed.     

Ultrastructural localization of fibronectin and laminin in the basement membranes of the murine kidney

Affinity-purified rabbit antibodies specific for two large noncollagenous gycoproteins--laminin and fibronectin--were used to study the distribution of these proteins in normal murine kidneys. Immunofluorescence staining of conventional frozen sections demonstrates fibronectin within mesangial areas of the glomerulus. Laminin is also found in mesangial areas. However, it also appears to be distributed in typical basement membranelike patterns on glomerular and tubular basement membranes and Bowman's capsule. At the ultrastructural level, by labeling 600-800-A thick frozen sections with a three-stage procedure consisting of specific antibodies, biotinyl sheep anti-rabbit IgG, and avidin-ferritin conjugates, fibronectin is present ony in the mesangial matrix and is specifically localized to areas immediately surrounding mesangial cell processes. Laminin, on the other hand, is found uniformly distributed throughout tubular basement membranes, the mesangial matrix, and Bowman's capsule. In glomerular basement membranes, laminin labeling is restricted to the lamina rara interna and adjacent regions of the lamina densa.     

Histogenesis and morphogenesis of epidermoid metaplasia in hamster tracheal organ explant culture

The formation of epidermoid metaplasia was studied in hamster tracheal epithelium in long-term serum-free organ explant culture. Explants were cultured up to 5 weeks in CMRL 1066 with antibiotics and amphotericin B. At 3 weeks there were rare small foci of epidermoid metaplasia and they became larger and more numerous at 4 and 5 weeks. Three dimensional reconstructions from serial sections demonstrated that the small deep-seated foci were discrete and did not reach the epithelial surface, whereas the larger foci were expansive and involved the full thickness of the explant epithelium. Each small focus consisted of a few swollen electron-lucent basal cells attached to the basal lamina, covered by a layer of flattened electron-dense secretory cells which formed a tight-fitting cap over the basal cells. The altered secretory cells displayed moderately well-developed rough endoplasmic reticulum and tonofilament bundles. During the early stages of formation the deep-seated metaplastic foci were completely covered by a layer of normal appearing cuboidal to low-columnar secretory and ciliated cells. Expansion of the metaplastic foci occurred by addition of flattened, electron-dense secretory cells to the cap so that multiple layers of altered secretory cells covered a core of basal cells, analogous to the structure of an onion. The secretory cells became cornified and with time the foci broke through the columnar mucociliary surface layer. In well-advanced foci, the uppermost cornified squames (metaplastic secretory cells) exfoliated into the tracheal lumen. The study emphasizes similarities and differences between the morphogenesis and histogenesis of epidermoid metaplasia in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)     

The contractile nature of the tubular-like cells of the parietal layer of the Bowman's capsule in male mice. An immunochemical and ultrastructural study.

The tubule-like cells (TLC) of the parietal layer of the Bowman's capsule of the renal corpuscle in normal male mice are provided with bundles of thin microfilaments (50-70 A). Moreover, the ultrastructural observations demonstrated that similar thin filaments (50-70 A) are located in the flattened cells of the parietal layer of the Bowman's capsule and in the tubular cells. All the above cells bind antimyosin-like antibodies. Considering the correspondence between the immunochemical and ultrastructural findings, it is suggested that the microfilaments located in TLC contain a 'myosin-like' protein.     

Ultrastructure of the nephron of the one-humped camel, Camelus dromedarius

The nephron of the one-humped camel Camelus dromedarius was investigated by light and transmission electron microscopy. Besides the many features common to other mammalian kidneys, the nephron of the camel is unique in having an unusually thick basal lamina underlying the epithelial cells of the nephron, the thickest being found in part of the parietal layer of Bowman's capsule and the thin limb of the loop of Henle. In the latter, the membrane usually appears lamellated and contains numerous tiny vesicles. In other parts of the nephron, the basal lamina usually has a homogenous appearance. The possible significance of the thickening of the basal lamina is discussed in relation to the general high renal efficiency of the camel.