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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In these experiments, we tested the hypothesis that chloroquine, a lysosomotropic agent which modifies protein and lipid metabolism by hepatocyte lysosomes, would alter the biliary excretion of lipids and lysosomal enzymes. We treated male rats for 5 days with intraperitoneal chloroquine (50 mg/kg body wt, n = 9) or saline (n = 8) and collected bile for 6 h via bile fistulas; rats were then killed and livers homogenized for biochemical analyses or processed for electron microscopy. Chloroquine markedly increased the biliary excretion of three lysosomal enzymes (mean +/- SEM) expressed as milliunits of activity per gram liver: N-acetyl-beta-glucosaminidase (24.4 +/- 2.7 vs. 12.5 +/- 1.4, p less than 0.01), beta-glucuronidase (26.4 +/- 4.7 vs. 10.9 +/- 1.4, p less than 0.01), and beta-galactosidase (9.8 +/- 1.7 vs. 5.5 +/- 0.8, p less than 0.05). In contrast, biliary outputs of enzymes associated with other organelles (e.g., alkaline phosphodiesterase I and lactic dehydrogenase) were unaffected by chloroquine treatment. Biliary cholesterol secretion was decreased after chloroquine administration (0.28 +/- 0.02 mumol/g liver vs. 0.39 +/- 0.03 mumol/g liver, p less than 0.01), but bile acid and phospholipid secretion were not altered; as a result, cholesterol saturation of bile decreased by 22% (p less than 0.05). Hepatic activities of all three lysosomal enzymes were increased after chloroquine administration (p less than 0.04); activities of enzymes associated with mitochondria, plasma membrane, endoplasmic reticulum, and cell sap were not altered. Morphometric analysis of electron micrographs of rat livers demonstrated a marked increase (p less than 0.001) in the number of lysosomelike vesicles and autophagic vacuoles in the vicinity of bile canaliculi after chloroquine administration; also, the number of canalicular microvilli decreased (p less than 0.003) after chloroquine treatment. We conclude that altered hepatic lysosomal morphology and function after chloroquine is accompanied by marked changes in outputs of lipids and lysosomal enzymes into bile. These findings call attention to a possible role for hepatic lysosomes in modulating biliary protein and lipid secretion.
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PMID:Effect of chloroquine on the form and function of hepatocyte lysosomes. Morphologic modifications and physiologic alterations related to the biliary excretion of lipids and proteins. 641 91

Teleost fishes, Arius Spixii and Salmo trout and adult Swiss albino mice have been processed with the freeze-fracture technique for SEM to explore the inner cytoplasmic and nuclear surface details of neurons and neuroglial cells. The specimens were fixed by vascular perfusion with Karnovsky fixative and 2-3 mm thick cerebellar slices were subsequently fixed by immersion in the same fixative. They were postfixed in osmium tetroxide, dehydrated in ethanol, frozen in Freon 22, cooled by liquid nitrogen and fractured. After thawing in ethanol, they were critically point dried, coated with gold-palladium and viewed by SEM. The surface features of perikaryon were examined at low resolution and magnifications. The image of endoplasmic reticulum, GERL complex and chromatin were described in fractured cerebellar neurons (granule and Golgi cells). The fractured protoplasmic astrocytes displayed a characteristic glass surface appearance of cytoplasmic body and processes, which facilitated their recognition at the neuropile and perivascular region. The oligodendrocytes appeared as fusiform cells depicting a thin rim of perinuclear cytoplasm. The surface view of endoplasmic reticulum was well studied at the nuclear poles. Fine cytoplasmic beaded canaliculi appeared connecting the outer surface of nuclear envelope with the plasma membrane inner surface. The nucleus exhibited well developed peripheral heterochromatin masses forming anastomotic bands separated by vacuolar spaces. The SEM nerve and neuroglial cell fractographs were compared with similar images obtained by conventional transmission electron microscopy and freeze etching technique.
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PMID:Low resolution scanning electron microscopy of cerebellar neurons and neuroglial cells of the granular layer. 650 21

Samples of teleost cerebellar cortex (Arius Spixii and Salmo Trout) fixed by immersion and vascular perfusion techniques were processed for light microscopy, SEM and TEM. SEM fractographs of endothelial cell nuclear, organelle and peripheral cytoplasmic zones have been compared with their corresponding TEM images. A simultaneous three-dimensional view of the luminal surface of endothelial cells at the nuclear zone, and inner details of heterochromatin structure was obtained. Chained micropinocytotic vesicles and deep cytoplasmic invaginations were observed. Surface connected micropinocytotic vesicles or vacuoles show stomas open to the luminal surface. Clear and dense endothelial micropinocytotic vesicles and vacuoles were observed at TEM level. The dense plasma substance can be used as an endogenous electron dense tracer for permeability studies. At SEM level the rough endoplasmic reticulum appears as a trabecular continuous system. The endothelial cytosol exhibits a smooth, glass surface appearance. The endothelial luminal surface changes its aspect according to the fixation procedure. The SEM and TEM aspect of endothelial junctions further supports their role as the morphological counterpart of blood-brain barrier. The basement membrane exhibited a homogeneous matrix and short or long neuropilar projections. Clear perivascular astrocytes with anastomotic processes form the main framework of perivascular neuropile. Like the peripheral endothelial cytoplasm, they exhibited dense and clear micropinocytotic vesicles and vacuoles, providing evidence for their transport function between capillaries and neighbouring brain parenchyma. The SEM appearance of their outer surface further supports their barrier function.
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PMID:Light, scanning and transmission electron microscopy study of fish cerebellar capillaries. 663 43

A new specimen preparation to reveal intracellular structures is introduced and its application to some tissues is demonstrated. By this method, intracellular structures are easily observed by SEM. Moreover, some parts of the cells and tissues are cleaved and dissociated, and interesting structures are revealed. Tissues are fixed with 1% osmium tetroxide, rinsed with distilled water and freeze cracked with 50% DMSO. The cracked specimens are rinsed with distilled water to remove cytoplasmic matrix. The author calls this method "Osmium-DMSO-distilled Water method (O-D-W method)". When prepared by this method, intracellular structures such as mitochondria and endoplasmic reticulum are easily demonstrated three-dimensionally by SEM. Sometimes, the nucleus is removed during the specimen preparation procedure and endoplasmic reticulum around the nucleus is seen three-dimensionally. When cells and tissues are cleaved and dissociated, lateral surface of the intestinal epithelium and the reverse side of the microvillous border is also observed. Peritoneal cells lining the liver is also detached from the basement membrane and the surface of the basement membrane is exposed.
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PMID:Use of distilled water as a rinsing solution for intracellular observation by scanning electron microscopy. 663 50

Pancreas, double-fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin was cut into sections 0.5-1 micron thick. The sections were surface-etched in an oxygen plasma produced by exciting oxygen with a radio frequency generator. Structural components of exocrine and endocrine cells were morphologically investigated in the secondary electron image mode of the SEM. Moreover, in order to identify some cell components such as endocrine granules, the morphological image obtained of the etched surface by the SEM were compared with those seen in a TEM, using the serial sections from the same tissue block and at the same cellular level. For a microanalytical investigation, tissues were fixed with glutaraldehyde alone. The structural components of exocrine and endocrine cells were analyzed by SEM/EDX. A better resolution under the SEM was obtained of 0.5-0.8 micron thick sections after surface-etching in an oxygen plasma for 1 minute. Intracellular structures such as nuclear membranes, nucleolus, mitochondria, rough endoplasmic reticulum and zymogen granules were readily identifiable. Moreover, the internal structure of organelles such as cristae of mitochondria was recognized. In the serial sections, the mode of arrangement of intracellular structures in the SEM was well consistent with those in the TEM. The peaks of phosphorus, sulphur and calcium were clearly detected from the intracellular components such as nucleolus, nuclear membranes and secretory granules.
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PMID:Scanning electron microscopy and EDX analysis of exocrine and endocrine gland cells of rat pancreas surface-etched in an oxygen plasma. 676 46

Following 70% hepatectomy on rats the galactose elimination capacity, taken as a measure of the cytosolic liver function, was reduced from 2.55 +/- 0.48 to 1.27 +/- 0.19 (mean +/- SEM) mumol/min. Six hours later it was restored to control values. The prothrombin index, representing the function of the endoplasmic reticulum, was reduced from 1.13 +/- 0.02 to 0.34 +/- 0.02 (arbitrary units) after 12 h, and it was restored after 96 h. The rapid normalization of the initial fall in the capacity to metabolize galactose reflects a two- to three-fold increase of the galactose metabolizing capacity of the remaining liver. This study demonstrates that liver functions are dissociated in time following 70% hepatectomy in the rat, and that the galactose elimination capacity is restored before regeneration can compensate for the loss in liver cell mass.
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PMID:Quantitative liver functions after 70% hepatectomy. 680 Aug 22

A white cocoon membrane emanating from an inferotemporal focus in the iris stroma totally ensheathed a Binkhorst four-loop iris plane lens 18 months after implantation. The membrane was removed and studied by scanning (SEM) and transmission (TEM) electron microscopy. By SEM the external surface of the membrane was characterized by a fibrillar meshwork, with only an occasional scattered spindle-shaped or rounded inflammatory cell occupying the surface. One-micron plastic sections revealed both spindle and polyhedral heavily pigmented cells in the outer aspect of the membrane, and compressed elongated nonpigmented spindle cells scattered throughout the central portions. By TEM cells clinging to the outermost aspects were bipolar iris stromal melanocytes with small melanosomes, inactive fibroblasts, or histiocytes with cytoplasmic ruffles. The larger rounded pigmented cells in the superficial region were viable or degenerated iris pigment epithelial cells or macrophages. Most of the substance of the membrane was composed of collagen fibrils 100-500 A in diameter with and without 640 A periodicity; these fibrils were generally oriented parallel to the spindle cells but did not display distinct bundling or a lamellar architecture. The spindle cells in the center of the lesion were active fibroblasts with abundant rough-surfaced endoplasmic reticulum and scattered actin myofilaments; they contained rare small and large melanin granules indicative of phagocytosis. It has been concluded that the membrane was produced predominantly by iris stromal fibroblasts probably activated by the haptics of the IOL or McCanell suture.
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PMID:The ultrastructure of an IOL "cocoon membrane". 687 72

Striated muscle cells of frog sartorius and smooth muscle cells of guinea pig taenia coli were observed three-dimensionally by field emission type scanning electron microscope (FE-SEM) and freeze-fracture deep-etching replica (FFDE) method. By tearing at different preparative stages, various cellular structures appeared on SEM: the outer surface of cells, the inner surface of plasmalemma, and the interior of cells. On the inner surface of the plasmalemma of striated muscle, many caveolae, membranous structures and fine filaments were observed. Inside the cells myofibrils showed the characteristic banding pattern and on the thick filaments, a periodicity of 40 nm was observed. Along the myofibril, T-tubules and sarcoplasmic reticulum were seen with their regional differentiations. In smooth muscle cells, on the inner surface of the plasmalemma there were many caveolae, bundles of filaments and endoplasmic reticulum. The central part of smooth muscle cells were occupied by their nucleus, many microtubules, mitochondria and rough surfaced endoplasmic reticulum. By the FFDE method, observations on finer details were added to the SEM studies, including lateral projections of myosin filaments in striated muscles and fine filaments connecting thin myofilaments in smooth muscle cells. In the terminal cistern of the sarcoplasmic reticulum, networks composed of granular materials were observed.
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PMID:Three-dimensional observation on muscular tissues. 688 61

The cement gland of Rhodnius prolixus is an epidermally derived tubular gland consisting of a distal synthetic region and a proximal muscular duct region. The synthetic region consists of numerous secretory units joined to a central chitinous duct via cuticular ductules. Proteinaceous secretion, synthesized by the goblet-shaped secretory cell, passess through the delicate cuticular lattice of a ductule-end apparatus and out through fine ductules to the central duct. Secretory cells are rich in rough endoplasmic reticulum and mitochondria. Light microscopy, SEM and TEM reveal the delicate lattice-like end apparatus structure, its formation and relationship to the secretory cell. The secretory cell associates via septate junctions with a tubular ductule cell that encloses a cuticle-lined ductule by forming an elaborate septate junction with itself. The ductules are continuous with the cuticle lining of the large central duct that conveys secretion to the proximal area. The proximal muscular duct has a corrugated cuticular lining, a thin epithelium rich in microtubules and thick longitudinal, striated muscles which contrast during oviposition, forcing the secretion out. Histochemistry and electrophoresis reveal the secretion as proteinaceous.
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PMID:The ultrastructure of the female accessory gland, the cement gland, in the insect Rhodnius prolixus. 700 76

Spermatogenesis in a parthenogenetic type of P. westermani (Kerbert 1878) called P. pulmonalis (Baelz 1880) throughout this study, was observed by light microscopy (LM), scanning (SEM), and transmission (TEM) electron microscopy. During spermatogenesis, most of the cells became degenerated or malformed as a result of aberrations during spermatogenesis. Vacuolated cells were often found in the testicular lumen. In some nuclei of spermatocytes, synaptonemal complexes were formed and this indicated that some pairing of homologous chromosomes did occur, but only rarely. Cytophores in some rosettes were broken down into small fragments and the cells separated from each other. Norman spermatozoa were very rarely found in the testis and never in the seminal receptacle, where egg and vitelline cells were present instead. Throughout spermatogenesis, Golgi complexes, mitochondria, ribosomes, and endoplasmic reticulum were not abundant, and this suggested that cell activities and protein synthesis were greatly reduced.
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PMID:Ultrastructural studies on spermatogenesis in a parthenogenetic type of Paragonimus westermani (Kerbert 1878) proposed as P. pulmonalis (Baelz 1880). 709 41


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