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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human deciduous teeth undergoing physiologic root resorption were extracted and fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and transmission (TEM) electron microscopy, and for acid (ACPase) and alkaline phosphatase (ALPase) cytochemistry. The resorbant organ, rich in odontoclasts, cementoblasts, fibroblasts, and macrophages, formed prominent resorption lacunae in root dentin. SEM observations of resorption lacunae treated with trypsin solution showed islands of newly-formed cementum matrix in part of the resorbing dentin surfaces. Such cementum consisted of bundles of densely-arranged collagen fibrils and, in part, contained forming cementocytic lacunae and canaliculi. Active cementoblasts adjacent to odontoclasts on resorbing dentin surfaces showed cuboidal outlines and were characterized by the presence of numerous cisterns of rough endoplasmic reticulum, well-developed Golgi complexes, secretion granules, and many mitochondria. They sometimes formed a thin layer of cementoid and/or cementum matrix upon the resorbing dentin surface. These cementoblasts had ACPase-positive lysosomes in the cell bodies and exhibited intense ALPase activity along the plasma membranes of whole cell surfaces. These results suggest that, during root resorption, 1) active cementoblasts are present adjacent to active odontoclasts and 2) these cementoblasts are involved in remodeling the resorbing dentin surfaces.
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PMID:Possible role of cementoblasts in the resorbant organ of human deciduous teeth during root resorption. 214 74

The proximal portions of axons of large anterior-horn cells were investigated in the lumbar cords of 10 normal human autopsy cases. Light-microscopically, 81 myelinated axons were observed to be connected with the cell body. Of the 81 axons, 78 emanated from the cell body and 3 others originated in the proximal part of primary dendrites. As for normal-looking neurons (n = 77), the length of the axon hillock plus initial segment was 64.0 +/- 12.3 microns (average +/- SEM), ranging from 47.5 to 110.0 microns, while the diameter of the thinnest portion of the initial segment was 2.40 +/- 0.30 microns (average +/- SEM), ranging from 1.32 to 3.92 microns. Electron-microscopically, the predominant organelles of the axon hillock were mitochondria, neurofilaments which merged into the axon and occasional granular endoplasmic reticulum. A few synaptic boutons were found on the surface of the axon hillock. The cell membrane of the initial segment consisted of a layer of electron-dense material (undercoating). The cytoplasm contained many neurofilaments, running parallel to the longitudinal axis of the initial segment. Among the neurofilaments, lysosomes, smooth endoplasmic reticulum, dense bodies and vesicular profiles as well as mitochondria were seen. At the beginning of the myelin sheath, the axoplasm contained mitochondria, many neurofilaments and occasional lysosomes.
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PMID:Observation of the proximal portions of axons of anterior-horn cells in the human spinal cord. 228 86

To investigate the effects of the estrogenic insecticide chlordecone on the morphology of mouse choroid plexus, 4 different doses (100.0, 250.0, 500.0 and 1000.0 micrograms) of the chemical were administered intraperitoneally to groups of adult males. Concurrent with the chlordecone treatments, another group of males received 10.0 micrograms estradiol-17 beta; the control group was treated with sesame oil vehicle. After 15 days of daily chemical injections, the mice were terminated and the choroid plexus from fourth ventricle examined morphologically. Scanning (SEM) and transmission (TEM) electron microscopic examination of control choroid plexus showed the cuboidal epithelium profusely covered with microvilli. SEM examinations of choroid plexus epithelium after chlordecone treatments revealed dose-dependent, cell alterations that effected the microvilli and cell surfaces. After the highest chlordecone dose, microvilli were no longer visible, the choroidal cell membrane appeared either smooth or pitted and there was evidence of increased luminal debris. TEM observations of the same choroid plexus cells revealed vacuolated cytoplasm, dilated endoplasmic reticulum, vacuolated mitochondria with disrupted cristae and cellular degeneration. SEM and TEM examination of choroid plexus after estradiol treatments revealed similar cellular alterations to those recorded after chlordecone treatments. The possible significance of these data are discussed.
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PMID:Transmission and scanning electron microscopic study of chlordecone (Kepone) induced changes in the male mouse choroid plexus. 240 37

Intracellular structures of mouse mesothelial cells lining the small intestine were studied by scanning electron microscopy. Specimens were prepared by the freeze-polishing method which permitted demonstration of the attenuated thin layered organization of the intracellular structures. When the surface cell membrane had been partially turned over during the specimen preparation procedure, many pinocytotic vesicles were observed attached to the cytoplasmic side of the cell membrane. We also demonstrated the external side of the basal cell membrane on which many openings of the pinocytotic vesicles were clearly shown as those recognized on the free cell surface. Two adjacent pinocytotic vesicles often appeared fused together. The multivesicular vacuole formed by the congregation of the pinocytotic vesicles were sometimes recognized on the cytoplasmic side of the surface and basal cell membrane. On the nuclear surface, nuclear pores and polysomes were visible. From our SEM findings, we classified the rough endoplasmic reticulum into three types: type I, II and III. The type I rough endoplasmic reticulum was composed of flat cisternae with fenestration, the type II of polygonal flat cisternae without fenestration, and the type III of vesicular cisternae. Polysomal formation is evident in the type III, but less in the type I and II. All of the endoplasmic reticulum appeared connected each other forming a continuous system in the cell. Two kinds of the Golgi apparatus were recognized: a stretched type with highly extended Golgi cisternae and a shrunken type with less developed Golgi cisternae. In the latter, lots of Golgi vesicles were attached on the periphery of the cisternae, and the outermost cisterna was commonly fenestrated.
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PMID:Three-dimensional demonstration of the intracellular structures of mouse mesothelial cells by scanning electron microscopy. 254 61

Intracellular structures of rapidly frozen biological tissues were observed in 3-D under a low-temperature scanning electron microscope using a newly developed side-entry type cryo-holder. The present low-temperature SEM is simple, easy to operate and effective for observing biological materials at high magnification. Biological tissues (the pancreas, small intestine, brown adipose tissue and Harderian gland) freshly removed from the mouse were immediately frozen in liquid propane cooled with liquid nitrogen, and their surfaces were manually fractured using a precooled razor blade in liquid nitrogen before introducing the cryo-holder into the SEM. When intracellular structures were revealed after appropriate sublimation, the specimens were coated with gold using a metal evaporator fitted to the side of the microscope column at one of the specimen chamber ports. The cryo-holder was connected to a copper braid coming from a liquid nitrogen reservoir to maintain a low temperature. Using this method, intracellular structures such as the mitochondria and endoplasmic reticulum were demonstrated at high magnifications. Ribosomal granules were discerned on the rough endoplasmic reticulum of the pancreatic acinar cells. Granular substances, presumably elementary particles, were also recognized on the mitochondrial cristae of the brown adipose tissue. The method was particularly effective for studying the 3-D configuration of lipid droplets which had been difficult to preserve by chemical fixation.
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PMID:High-resolution low-temperature scanning electron microscopy for observing intracellular structures of quick frozen biological specimens. 259 47

The structure of the developing oocytes in the ovary of unfed and fed female Argas (Persicargas) arboreus is described as seen by scanning (SEM) and transmission (TEM) electron microscopy. The unfed female ovary contains small oocytes protruding onto the surface and its epithelium consists of interstitial cells, oogonia and young oocytes. Feeding initiates oocyte growth through the previtellogenic and vitellogenic phases of development. These phases can be observed by SEM in the same ovary. The surface of isolated, growing oocytes is covered by microvilli which closely contact the basal lamina investing the ovarian epithelium and contains a shallow, circular area with cytoplasmic projections and a deep pit, or micropyle, at the epithelium side. In more advanced oocytes the shell is deposited between microvilli and later completely covers the surface. Transmission EM of growing oocytes in the previtellogenic phase reveals nuclear and nucleolar activity in the emission of dense granules passing into the cytoplasm and the formation of surface microvilli. The cell cytoplasm is rich in free ribosomes and polysomes and contains several dictyosomes associated with dense vesicles and mitochondria which undergo morphogenic changes as growth proceeds. Membrane-limited multivesiculate bodies, probably originating from modified mitochondria, dictyosomes and ribosomal aggregates, are also observed. Rough endoplasmic reticulum is in the form of annulate lamellae. During vitellogenesis, proteinaceous yolk bodies are formed by both endogenous and exogenous sources. The former is involved in the formation of multivesicular bodies which become primary yolk bodies, whereas the latter process involves internalization from the haemolymph through micropinocytosis in pits, vesicles and reservoirs. These fuse with the primary yolk bodies forming large yolk spheres. Glycogen and lipid inclusions are found in the cytoplasm between the yolk spheres.
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PMID:Fine structure of the developing oocytes in adult Argas (Persicargas) arboreus (Ixodoidea: Argasidae). 270 11

The internal and surface ultrastructure and cytochemistry (MPO, AP) of the histiocytes from 16 patients were studied. The results showed that poorly differentiated histiocyte was irregular in cell contour with various projections. All had more or less neoplastic histiocytes in which numerous vacuoles and blisters along peripheral plasma membrane were seen. The neoplastic cells had numerous lysosomes, abundant short strands of rough endoplasmic reticulum, and free and poly-ribosomes in the cytoplasma. Long profiles and ring of RER as well as expansive forms were seen in 4 cases. The mitochondria were generally normal although an occasional elongated form and their cristae showed destroyed architecture in 6 cases. Occasionally, perinuclear bundles of microfilaments and prominent Golgi apparatus were seen. The nuclei of the neoplastic histiocytes were irregularly shaped and most had one or two huge nucleoli. Circular nuclear bodies were often seen. The ultrastructural cytochemistry of the neoplastic histiocytes showed: MPO was weakly positive in about 1/4 to 1/2 of the cells. AP reaction in all of the neoplastic histiocytes was always strongly positive located in the nuclear membrane. RER, lysosomes granules and Golgi apparatus. Under SEM, various surface characteristics of the neoplastic histiocytes were seen such as bleb-covered surface; bleb-ruffled surface, and ruffled surface.
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PMID:[Ultrastructural and cytochemical studies of malignant histiocytosis]. 276 55

Extracted human deciduous teeth undergoing physiological root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and analytical transmission electron microscopy, as well as acid trimetaphosphatase cytochemistry. The granulated tissues, which are rich in multinucleated odontoclasts and capillary vessels, formed various resorption lacunae on the resorbing dentin surfaces. SEM observations of dentin surfaces treated with sodium hypochlorite revealed two types of resorption lacunae: deep, round lacunae in which the peritubular matrix of dentinal tubules was strongly dissolved; and shallow, irregular lacunae with intact peritubular matrix. In trypsin-treated materials, the resorption surfaces were characterized by the presence of numerous collagen fibers in both the peritubular and intertubular matrices, suggesting demineralization of the surface dentin. Odontoclasts were characterized by the presence of abundant mitochondria, perinuclear stacks of Golgi membranes, various lysosomes, numerous endocytotic vacuoles, and a well-developed ruffled border against the resorption lacunae. Most endocytotic vacuoles were distributed in the cytoplasm between the ruffled border and the nuclei. In undemineralized ultrathin sections, the surface dentin of resorption lacunae consisted of collagen fibers and apatite crystals and had a lower packing density than those in unresorbed, deeper dentin. Many apatite crystals were demonstrated to be present in the extracellular channels of the ruffled border and in adjacent endocytotic vacuoles derived from it. Lysosomes located in the perinuclear cytoplasm of odontoclasts contained amorphous dense material and/or a small amount of crystals. An energy-dispersive x-ray microanalysis of apatite crystals in undemineralized sections indicated that the energy spectrum peaks of Ca and P detected from crystals in resorbing dentin were much lower than those in unresorbed dentin. Similarly, lower spectrum peaks of Ca and P were obtained from crystals found in the ruffled border and endocytotic vacuoles of odontoclasts. A slight trace Ca peak also was detected in the amorphous dense material in lysosomes of odontoclasts. The enzyme cytochemistry of lysosomal acid trimetaphosphatase indicated that odontoclasts had intense enzymatic activity in the Golgi membranes, endoplasmic reticulum cisternae, lysosomes, and endocytotic vacuoles. Dense reaction precipitates of enzymatic activity also were found along the dentin surfaces of resorption lacunae occupied by odontoclast ruffled borders.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Dentin resorption mediated by odontoclasts in physiological root resorption of human deciduous teeth. 285 Dec 63

The origin and mechanism of the secretion of membrane-bound particles in bovine seminal plasma were studied with transmission (TEM) and scanning (SEM) electron microscopy of the epididymis, vas deferens, ampulla, and seminal vesicle of adult bulls. In the SEM study, all these organs were found to contain apical protrusions in the lining of the epithelial cells. Eventually the protrusions became detached and formed secretory bodies within the lumina of these organs. In the epididymis, the TEM study disclosed a granular and rather homogeneous content in the protrusions and bodies, whereas in the vas deferens they contained dilated cisternae of smooth endoplasmic reticulum. In the ampulla and seminal vesicle, the formation of the apical protrusions was associated with an accumulation of membrane-bound vesicles. These vesicles were found to be released from the storage bodies into the secretory fluid of the lumen. Both could be harvested from isolated seminal vesicle secretions by Percoll gradient centrifugation. It was concluded that various parts of the bovine reproductive organs discharge their secretory products at least partly by an apocrine mechanism. The membrane-bound particles in the seminal plasma, however, appear to be mainly derived from the ampulla and seminal vesicle.
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PMID:Electron microscopic study of the secretion process in bovine reproductive organs. 323 78

The calcium content of synapses of parallel fibers on Purkinje cell dendritic spines was determined by electron probe x-ray microanalysis of freeze-dried cryosections from directly frozen slices of mouse cerebellar cortex. In fresh slices frozen within 20-30 sec of excision, calcium concentrations ranging from 0.8 to 18.6 mmol/kg of dry weight were measured in cisterns of smooth endoplasmic reticulum within Purkinje cell dendritic spines. The average calcium content of spine cisterns in rapidly excised slices (6.7 +/- 0.6 mmol/kg of dry weight +/- SEM) was higher than the average calcium content of spine cisterns in brain slices incubated without stimulation for 1-2 hr before direct freezing (2.5 +/- 0.4 mmol/kg of dry weight). Depolarization of incubated cerebellar slices by isotonic 55 mM KCl resulted in the accumulation within spine cisterns of very high amounts of calcium or isotonically substituted strontium, both derived from the extracellular fluid. These results suggest that one function of spine cisterns is to sequester free calcium that enters the spine through ligand-gated or voltage-gated channels during synaptic transmission.
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PMID:Activity-dependent accumulation of calcium in Purkinje cell dendritic spines. 342 55


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