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E Reale

Publications and source records attributed to E Reale.

At least 37 records · Page 2Linked to original sources
PubMed1993

Further observations on the morphological alterations of the glomerular capillary wall of the rat kidney caused by chemical and physical agents: standard procedures versus quick-freezing and freeze-substitution.

The purpose of the present study was to pin-point which of the various preparatory steps required by different histological procedures (conventional, cryosubstitution, freezing followed by cryosubstitution or replication) induces alterations in the fine structure of the endothelial and epithelial surface coat (SC) and of the interposed glomerular basement membrane (GBM). Samples of rat kidney cortex prefixed by vascular perfusion, and isolated glomeruli fixed by immersion, were used. The results demonstrate a continuous, homogeneous and amorphous SC and a GBM devoid of laminae rarae when freezing is used and followed either by cryosubstitution and embedding or by fracture, deep etching and replication. Postfixation in OsO4, and especially dehydration in organic solvents at room temperature, generate a filamentous SC and a GBM with laminae rarae. The different morphology may be due to an extraction of glycoconjugates from SC and GBM during postosmication and/or especially to precipitation of these components during dehydration by organic solvents at room temperature. Studies on isolated glomeruli show comparable results and, in addition, demonstrate that the distance of the capillary loop from the surface of the block influences the morphology of SC and GBM. Rinsing the vascular bed before isolation does not induce a loss of SC or GBM components.

Acetone↗
PubMed1993

Isolated brush cells of the rat stomach retain their structural polarity.

The brush cells (BC) are highly polarized elements occurring in epithelia of endodermal origin. They have a preferential topographical distribution in the organs in which they reside. In the stomach of the rat, BC prevail near the transitional zone separating the forestomach from the glandular stomach. Thus, a method was developed to isolate and recover BC from this organ with the aim of investigating the changes they may undergo after dissociation. Strips of the rat stomach were severed from the very proximal border of the glandular region and incubated in Hanks' balanced salt solution containing pronase. After sedimentation of the dissociated cells (crude sediment containing all stomach epithelial cell types) two successive cell fractions were prepared on performed Percoll gradient in an attempt to enrich BC in a defined layer. BC were recovered in a fraction at a density close to 1.03 g/ml where they represented about 2% of all cells. The isolated BC changed their form from columnar to pear-shaped; however, they maintained their structural polarity over 2 h as demonstrated by light microscopy, transmission-and scanning-electron microscopy. The fine structure of BC was always satisfactorily preserved. Maintenance of the structural polarity of isolated BC is contrary to the general rule according to which all conventional epithelial cells examined to date lose their polarity after isolation. This result is discussed in relation to morphological findings in isolated sensory cells (hair cells, photoreceptor cells) leading to the suggestion that BC are more similar to these than to conventional epithelial cells.

Animals↗
PubMed1992

Alterations in the morphology of glycoconjugate molecules caused by histochemical procedures: comparison of renal glomeruli and articular cartilage.

The fine structure of the glycoconjugate molecules was investigated in the glomerular capillary wall of the rat kidney fixed by vascular perfusion, and in the human and rat articular cartilage fixed by immersion. Kidney and cartilage were either prefixed in aldehyde alone (group a), or with the addition of Alcian Blue 8 GX (group b), or Alcian Blue and 0.3 M MgCl2 (group c), or Acridine Orange at a low (0.01%) and high (0.1%) concentration (group d). The specimens were postfixed either in OsO4 phosphate or cacodylate, with the exception of some of the samples in group a, for which a solution of potassium ferrocyanide-reduced OsO4 was used (group e). All samples were conventionally dehydrated and embedded in Epon. In addition, some of the tissue samples in group c were cryoprotected, frozen in liquid Freon (-150 degrees C) or in nitrogen slush (-210 degrees C), both postfixed and dehydrated by cryosubstitution, and embedded in Epon (group f). The present investigations demonstrate that some well known extracellular structures such as the laminae rarae of the glomerular basement membrane or the interfibrillar matrix of the articular cartilage can be considerably altered in their morphology by the histological procedures applied. Whereas the precipitated glycoconjugates, as seen after staining with cationic dyes or reduced OsO4 and conventional dehydration, can easily be recognized, the superposition of the extended molecules, as preserved by freezing and substitution, prevents their demonstration in native conformation.

Adolescent↗
PubMed1992

The "limiting ridge" of the rat stomach.

In the rat, the forestomach is separated from the glandular stomach by a fold of the forestomach mucosa which generates the "limiting ridge" on the inner surface of the organ. This ridge overlaps a deep groove which is flanked proximally by the forestomach and distally by the glandular stomach. Light microscopy and scanning electron microscopy reveal that the keratinized squamous epithelium of the forestomach merges into the columnar epithelium of the glandular stomach at the bottom of the groove. Among the columnar cells of the distal wall of the groove are numerous brush cells. A remarkably thick lamina muscularis mucosae extends deep into the ridge. The peculiar architecture of the "limiting ridge" and the presence of numerous brush cells in its distal wall suggest that the region not only represents the transitional zone between forestomach and glandular stomach but that it might have a more specific function.

Animals↗
PubMed1991

Fine structure of the elasmobranch renal tubule: neck and proximal segments of the little skate.

This is the first in a series of studies that examines the renal tubular ultrastructure of elasmobranch fish. Each subdivision of the neck segment and proximal segment of the renal tubule of the little skate (Raja erinacea) has been investigated using electron microscopy of thin sections and freeze-fracture replicas. Flagellar cells, characterized by long, wavy, flagellar ribbons, were observed in both nephron segments. They were found predominantly in the first subdivision of the neck segment, which suggests that propulsion of the glomerular filtrate is a primary function of this part of the renal tubule. In the non-flagellar cells of the neck segment (subdivisions I and II), there were bundles of microfilaments, a few apical cell projections, and, in subdivision II, numerous autophagosomes. In the proximal segment, the non-flagellar cells varied in size, being low in subdivision I, cuboidal in II, tall columnar in III, and again low in IV. Apical cell projections were low and scattered in subdivisions I and IV and were highest in III where the basolateral plasma membrane was extremely amplified by cytoplasmic projections. Furthermore, in these cells the mitochondria were numerous with an extensive matrix and short cristae. A network of tubules of the endoplasmic reticulum characterized the apical region of the non-flagellar cells in subdivisions I, II, and IV. In the late part of subdivision II and the early part of III, the cells were characterized by numerous coated pits and vesicles, large subluminal vacuoles, and basally located dense bodies, all of which are structures involved in receptor-mediated endocytosis. Freeze-fracture replicas revealed gap junctions restricted to the cells of the first three subdivisions of the proximal segment. The zonulae occludentes were not different in the neck and proximal segments, being composed of several strands, suggesting a moderately leaky paracellular pathway.

Animals↗
PubMed1991

The fine structure of the elasmobranch renal tubule: intermediate, distal, and collecting duct segments of the little skate.

Sharks, skates, and rays (Elasmobranchii) have evolved unique osmoregulatory strategies to survive in marine habitats. These adaptations include a complex renal countercurrent system for urea retention. The fine structure of the complete renal tubular epithelium has yet to be elucidated in any species of cartilagenous fish. The present study, which is a companion to our recent paper describing the ultrastructure of the neck and proximal segments of the elasmobranch nephron, uses thin sections and freeze-fracture replicas to elucidate the fine structural organization of the intermediate, distal, and collecting duct segments of the little skate, Raja erinacea, renal tubule. The epithelium of the intermediate, distal, and collecting duct segments consists of two major cell types: nonflagellar cells, the major epithelial cell type; and flagellar cells, described elsewhere. The intermediate segment consists of six subdivisions lined by cuboidal-columnar cells with variously elaborated microvilli and interdigitations of lateral and basal cell plasma membranes, as well as some subdivisions with distinctive vesicles and granules. The distal segment consists of two subdivisions, both of which are lined by a simple epithelium, and are distinguished from each other by their distinctive contents; dense bodies and granules. The collecting duct segment also has two subdividions, the first lined by a simple columnar epithelium and the second by a stratified columnar epithelium. Both subdivisions have apical secretory granules. The present findings show a more highly specialized and diverse epithelium lining the renal tubule of these cartilagenous fish than is found in either of the "adjacent" phylogenetic taxa, Agnatha or Ostheichthyes, suggesting significant differences among these groups in transepithelial transport mechanisms and renal function.

Animals↗
PubMed1991

Elastic-like tissue, a new component of the renal glomerular capillary wall in a cartilaginous fish.

Elastic-like tissue composed of tubular microfibrils continuous with, and disappearing into, amorphous material is present in the connective tissue space of the glomerular capillary wall of the river ray (freshwater elasmobranch) kidney. The amorphous material is stained by tannic acid but not by uranyl acetate. Structures with similar morphology and staining characteristics are also found in the subendothelial connective tissue layer of renal arteries in this species. Comparative ultrastructural observations of kidneys from marine rays show elastic-like tissue in the arterial wall but not in the glomerular vessels.

Animals↗
PubMed1991

Ultrastructural changes in the blood-brain barrier after nimodipine treatment and induced hypertension.

Fourty-four narcotized rats were split into two equal groups, one being treated with nimodipine and the other with a placebo. By use of norfenefrine the blood pressure was raised to values of 150 and 180 mm Hg within the limits of the autoregulation of brain perfusion and under continuous measurement. Fifteen minutes after application of the standard tracer, horseradish peroxidase, the animals were exsanguinated using a saline perfusion and then perfusion-fixed with Karnovsky's solution. After development of the peroxidase staining the brain sections were evaluated and then allocated to their respective groups. In brain tissues from the experimental group significantly more frequent perivascular accumulations of horseradish peroxidase reaction product were found (P less than 0.001). In electron micrographs it could be seen that the tight junctions were intact and that there was a neuroendothelial transport, with horseradish peroxidase-filled vesicles, in the endothelium, muscle cells, and brain parenchyma. These vesicles represent a medium of transport for all proteins of high molecular weight and can therefore result in brain edema. It is concluded that nimodipine damages the blood-brain barrier by disturbance of the autoregulation of the cerebral blood flow.

Animals↗
PubMed1991

Histochemical localization of glycoconjugates in the palmar aponeurosis of Dupuytren's patients.

Acridine orange added to the primary fixative or reduced osmium tetroxide as postfixative have been used in order to localize by thin section electron microscopy glycoconjugates in the extracellular matrix of the normal palmar aponeurosis as well as in tissues at different stages of Dupuytren's contracture. After use of acridine orange or reduced osmium tetroxide, in the nodule of the active stage an extensive network of fine filaments separated single or small bundles of collagen fibrils from each other. In the cord of the residual stage fixed in presence of acridine orange, the tightly packed collagen fibrils in the central region of the specimens were swollen and had stained material interposed between the single microfibrils. In specimens of the same cord first fixed with glutaraldehyde alone, followed by reduced osmium tetroxide, the disaggregation of collagen fibrils could be seen only occasionally and the intrafibrillar stained glycoconjugates were less evident. Comparable alterations were absent from the normal tissue. The possible reasons of these differences are discussed.

Acridine Orange↗
PubMed1991

The glomerular filtration barrier of the kidney in seven vertebrates classes. Comparative morphological and histochemical observations.

In the mammalian kidney, the glomerular filtration barrier (GFB) is mostly composed of endothelial and epithelial cells with the glomerular basement membrane interposed. In lower vertebrates, extensive regions of the GFB consist of the endothelial and epithelial cells, each lying on its own basement membrane. These two basement membranes border the mesangium, which contains mesangial cells (surrounded by its own discontinuous basement membrane), microfibrils and collagens (cross-striated fibrils, anchoring fibrils, and 5 nm interfibrillar filaments). Occurrence and extension of these mesangial components decrease from fish to mammals. Anionic binding sites associated with the different structures of the GFB of all animal species have been demonstrated by using dyes such as Alcian blue (with or without addition of electrolytes), Ruthenium red or Safranine O. The surface coat of endothelial and epithelial cells, the laminae rarae (interna and externa) of the glomerular basement membrane, the laminae rara and diffusa (wherever distinct endothelial and epithelial basement membranes occurred) as well as the collagen fibrils show particles (with polycationic dyes) or filaments (with monocationic dyes). The mesangial microfibrils are usually well preserved and intensively stained.

Animals↗
PubMed1991

Ultrastructural changes of the patellar tendon as a cruciate ligament substitute (one year and two year results).

In four black-faced sheep, the posterior cruciate ligament was replaced with a free autogenous patellar tendon transplant. Tissue samples from the transplants were investigated by light and electron microscopy 1 year and 2 years after surgery. The normal contralateral posterior cruciate ligament and the normal contralateral patellar tendon were used as controls. The structural differences concerned cells, collagen fibrils, elastic tissue and proteoglycans. Most of the cells of the contralateral patellar tendon were spindle-shaped, whereas those of the transplant were frequently chondroid. In the central region of the transplant as well as in the area far from the bone, cell degenerations, and occasionally hypo- or even acellular zones were found. Measurements of the diameter of collagen fibrils in both contralateral patellar tendon and posterior cruciate ligament showed a more or less pronounced bimodal distribution. A unimodal distribution with mainly thin fibrils (20-60 nm) was demonstrated in the transplant tissue which also revealed some morphological alterations of the collagen fibrils. Thin elastic fibers (microfibrils and amorphous material) were randomly scattered among the collagen fibrils of the control samples, bundles of microfibrils (without amorphous material) characterized the transplant. Staining with Alcian blue in the presence of 0.3 M MgCl2 demonstrated a close relationship between proteoglycans and collagen fibrils as well as elastic components in patellar tendon. This arrangement was lost in the transplant where abundant proteoglycans were revealed which, however, composed a tight irregular network between the collagen fibrils. The results serve as a baseline for understanding the impaired biochemical properties of a free autogenous patellar tendon transplant.

Animals↗
PubMed1990

The presence of a juxtaglomerular apparatus in elasmobranch fish.

UNLABELLED: Previous studies have concluded that a juxtaglomerular apparatus evolved in phylogenetic groups "higher" than elasmobranch fishes. The present study shows for the first time a distinct juxtaglomerular apparatus in four marine elasmobranchs, the spiny dogfish Squalus acanthias), the smooth dogfish (Mustelus canis), the little skate (Raja erinacea), and the cownose ray (Rhinoptera bonasus). Serial semithin sections of these fishes' kidneys reveal the four morphological components of a juxtaglomerular apparatus at the vascular pole of the renal corpuscle: (1) an afferent arteriole surrounded by smooth muscle cells which have granules containing a material exhibiting a periodic substructure comparable to that of renin granules in higher vertebrates; (2) an efferent arteriole usually devoid of smooth muscle cells but having pericyte-like cells; (3) a macula densa portion of the distal tubule juxtaposed between the afferent and efferent arterioles; and (4) elongated, fusiform cells (Goormaghtigh cells), which are in continuity with similar cells of the abundant intra-glomerular mesangium, and fill the space bordered by the distal tubule and by the afferent and efferent vessels. The distal tubule, from the site where it lies close to the afferent arteriole, moves directly toward the urinary pole, frequently indenting the renal corpuscle. Within this indentation, the tubule may be flanked by the efferent vessel, by the extraglomerular mesangium, or by Bowman's capsule only. Facing these structures the tubular epithelial cells possess basally dilated intercellular spaces. Endothelial cells of the efferent vessel(s) are fenestrated, possessing pores which are closed by a diaphragm. CONCLUSION: marine elasmobranch fish possess the morphological components of a juxtaglomerular apparatus which suggests that these fishes, like most other vertebrates, possess a renin-angiotensin system and a glomerular-tubular feedback mechanism.

Animals↗
PubMed1990

Brush cells of the mouse gallbladder. A correlative light- and electron-microscopical study.

The brush cells (BC) of the mouse gallbladder were studied using light and electron microscopy (transmission and scanning) to determine their shape and distribution. Specimens were fixed in glutaraldehyde and postfixed in ferrocyanide-reduced osmium tetroxide. BC selectively stained with toluidine blue could be identified by means of light microscopy and subsequently studied in serial semithin and ultrathin sections. The results revealed that the shape of the BC is flask-like. A slender, occasionally branched cytoplasmic process emerges from the bulk cell body and extends through the basal region of neighboring epithelial elements to the basement membrane. Examination of the entire gallbladder epithelial surface by scanning electron microscopy revealed that the BC are numerous in the neck region of the organ but only scanty or even absent in wide areas of the corpus region. Their number increases again in the fundic region. These results demonstrate a preferential regional distribution of BC in the gallbladder, which is discussed in relation to a possible functional significance of the BC.

Animals↗
PubMed1990

The reaction of acridine orange with proteoglycans in the articular cartilage of the rat.

Acridine Orange in concentrations from 0.01% to 0.2% was added to the first fixative solution in order to stain vibratome sections and small blocks of the articular cartilage of 2 month old rats. The interterritorial matrix of the radial or deep zone (zone 3) was examined. It contained reaction products with different morphology depending on the specimens used. In vibratome sections filaments were seen arranged in a homogenous pattern and changing in size with the concentration of the dye: diluted solutions produced finer filaments than concentrated ones. In contrast, in tissue blocks the staining pattern was not altered by different concentrations of Acridine Orange. However, with increase of the distance from the surface of the specimens the size of the filaments gradually decreased and formed a finer network. Since after preincubation with chondroitin ABC lyase only minute reaction products remained, an interaction of the dye with the sulphated glycosaminoglycans of the proteoglycans in the articular cartilage is suggested. The experiments show that by using mainly monocationic monomers of Acridine Orange the proteoglycans can be stained in a more expanded state than with polycationic dye polymers.

Acridine Orange↗