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Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of three widely used glutaraldehyde-based fixatives on cellular volume and structure have been studied utilizing TEM, SEM, time-lapse micrography during the fixation procedure, volumetry and demonstration of the lysosomal enzyme acid phosphatase. The cells used were in vitro cultivated human glia and glioma cells and suspensions of isolated rat liver parenchymal cells. The fixatives compared were the following: 2 per cent glutaraldehyde (GA) in 0.1 M Na-cacodylate-HCL buffer (cac) with 0.1 M sucrose (pH 7.2); total osmolality (T) 510 mOsmol; vehicle osmolality (V) 300 mOsm, 2 per cent GA in 0.1 M cac (pH 7.2; T = 410 mOsmol; V = 200 mOsmol) and 1.5 per cent GA in 0.067 M cac with 0.033 M sucrose (pH 7.2; T = 320 mOsmol; V = 170 mOsmol). It was found that the fixative with a vehicle osmolality of 300 mOsmol gave results which were interpreted as ideal while the two fixatives were hypotonic vehicles resulted in changes which were easily demonstrated during volumetry, time-lapse micrography, SEM and cytochemistry. However, the differences observed in the TEM were less obvious and difficult to interpret, the major alternations being changes in the configuration of the ER in the liver cells. In conclusion, our findings show that even small variations in the composition of a glutaraldehyde fixative can result in structural changes which do not correspond to the functional morphology of a living cell. Such changes make correct interpretation of micrographs difficult.
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PMID:A comparison of the effects of three widely used glutaraldehyde fixatives on cellular volume and structure. A TEM, SEM, Volumetric and Cytochemical Study. 40 40

The effects of prostaglandin E1(PGE1), prostaglandin synthesis inhibitor and indomethacin (IN) on the growth and metastasis of Lewis lung carcinoma (LLC) were studied and their mechanisms of action were investigated. Seventy-five C57BL mice of both sexes were utilized in the experiment. It was found that both PGE1 and IN could significantly retard the growth of transplanted LLC and reduce the number of pulmonary metastatic foci. PGE1 obviously decreased the acid phosphatase (ACP) activity of LLC cells while IN showed no such effect. Besides, PGE1 could markedly elevate the plasma cAMP level of LLC-bearing mice, but not normal controls. Meanwhile, it could decrease plasma cGMP concentration of both normal and tumor-bearing mice. IN, like PGE1, could increase plasma cAMP and decrease plasma cGMP levels of LLC-bearing animals. TEM observation revealed that tumor cells treated with PGE1 and IN presented a series of degenerative and destructive changes. In addition, PGE1 and IN exhibited a different effect on several cell-mediated immune responses of the tumored hosts, the former inhibitory and the latter stimulatory. The possible mechanisms of action of the two chemicals are discussed.
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PMID:The inhibitory effects of prostaglandin E1 and indomethacin on the growth and metastasis of transplanted Lewis lung carcinoma in C57BL mice. 216 65

The interaction between conidia of Fonsecaea pedrosoi and mouse resident peritoneal macrophages was observed by light microscopy and by scanning (SEM) and transmission (TEM) electron microscopy. The conidia first attached to the surface of the macrophage and were then ingested. Prolonged incubation of the macrophage cultures showed proliferation of intracellular fungi as well as those which remained attached to the macrophage surface. The conidia were ingested by a typical phagocytic process, with formation of a phagosome. Macrophage lysosomes were observed to fuse with the phagosomes by immunofluorescence microscopy of macrophages previously labeled with acridine orange, by TEM of thin sections of macrophages labeled with albumin-gold, and by ultrastructural localization of acid phosphatase within the phagosomes.
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PMID:Fine structure and cytochemistry of the interaction between Fonsecaea pedrosoi and mouse resident macrophages. 228 84

Cultured cells derived from a mouse adrenocortical tumor transplant are unspecialized in appearance, but produce basal levels of steroids and demonstrate a near-immediate steroidogenic response to ACTH. There is biochemical evidence that ACTH induces increases in the uptake of serum lipoproteins by these cells and that this material is hydrolyzed in lysosomes to free cholesterol, a precursor for steroid end products. To investigate morphologically the role of lysosomes in the steroidogenic activity of these cells, cultures were incubated for 4 h with and without ACTH, then processed for the ultrastructural localization of acid phosphatase (ACPase), a marker enzyme for lysosomes, and for GERL, the lysosome-forming subcompartment of the Golgi, and examined by TEM and HVEM. Steroid output was determined by a fluorometric technique. Unstimulated cells secreted basal levels of steroids. By TEM, large endosomes, some containing semi-compact material and ACPase reaction product, were occasionally seen at the cell periphery and in the Golgi region. The Golgi and GERL were poorly developed. Residual bodies, a few of them ACPase+, appeared in the Golgi region and in microtubule-associated clusters near the cell membrane. ACTH-stimulated cells secreted steroids at 8-10 fold basal values. In TEM records, they displayed numerous ACPase+ endosomes between the cell periphery and the Golgi. The Golgi and GERL regions appeared to be hypertrophied and many large, inclusion-containing, strongly ACPase+ residual bodies appeared here and in elongated microtubule-containing cell processes. HVEM micrographs showed more definitively that ACTH produced distinct increases in the size of GERL and in the number of ACPase+ organelles. Our results suggest that in unstimulated cells, endosomes, presumably containing media-derived material, gain lysosomal enzymes in or near GERL, are transformed to residual bodies as their contents are hydrolyzed, and are subsequently translocated by microtubules to the cell periphery for exocytosis. ACTH appears to intensify all of these effects. The "giant" lysosomes seen in stimulated cells may result from a fusion of smaller lysosomes. Their amorphous contents may reflect an inefficient hydrolysis of LDL to free cholesterol.
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PMID:The effects of ACTH on acid phosphatase activity in endosomes, GERL and lysosomes of cultured adrenal tumor cells. 287 77

Lung alveolar macrophages (LAM), obtained by bronchoalveolar lavage of healthy donors, were separated into four subfractions on discontinuous gradients of Percoll and subjected to light microscopic, transmission (TEM) and scanning electron microscopic (SEM) studies. Alveolar macrophage morphometric analysis was performed on cytocentrifuged preparations. TEM of subpopulations revealed considerable morphologic heterogeneity. By SEM, cells of the most dense (D) subfraction were small, round, and, typically, the surface was highly ruffled with small membrane pseudopods. Cells of the least dense subfraction (A) showed a low degree of membrane folding or filopodia and were often totally disorganized. In smokers, macrophages of fraction A had a greater area and perimeter compared with non-smokers, whereas the inverse relationship was observed for C and D cells. Also, the number of electron-dense inclusions and the level of acid phosphatase were higher in smokers than in non-smokers. Coupled with functional heterogeneity the morphologic differences described in this paper suggest that density-separated subpopulations of LAM may represent different stages of differentiation or maturation.
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PMID:Subpopulations of human lung alveolar macrophages: ultrastructural features. 291 37

The cytochemical localization of enzymatic activity by means of backscattered electron imaging (BEI) is reviewed and the application of BEI to changes in acid phosphatase and ATPase distribution during physiological (programmed) cell death in Heliothis midgut is explored. Programmed cell death entails the release of nascent free acid phosphatase as extracisternal hydrolase. This shift can readily be detected by means of the atomic number contrast imparted by BEI of the lead phosphatase reaction product, thus enabling the distribution of dying cells to be mapped. BEI is particularly useful in this context as it allows the examination of bulk specimens at low magnification. Death of cells is also accompanied by a collapse in ATPase activity which shows up as cytochemically negative areas in the X-ray microscope and by means of BEI. Acid phosphatase in normal cells is localized in the apical microvilli and lysosomes. Senescent or dying cells, however, clearly show a basally situated free hydrolase which migrates throughout the cell. Parallel TEM results confirm that this enzyme is ribosomal and extracisternal rather than lysosomal in origin. ATPase activity is largely limited to the apical microvilli, although there is some activity associated with the basal plasma membranes. The apical ATPase, however is partially resistant to ouabain. Young and mature cells are positive although in the latter case some microvilli may be lost as the cells acquire a negative cap or dome. Inhibition by bromotetramizole indicates that apical activity is not to any significant extent contributed to by alkaline phosphatase. Degenerate or dead cells are negative and can be seen as a mozaic of "black patches" among normal cells when imaged by means of BEI or X-ray microscopy.
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PMID:The use of backscattered electron imaging, X-ray microanalysis and X-ray microscopy in demonstrating physiological cell death. 297 76

The histochemistry and ultrastructure (SEM and TEM) of the spermatheca of Biomphalaria glabrata was investigated to elucidate the function of this organ and to compare its structure and function to similar organs found in other species. The spermatheca has a debris-filled lumen surrounded by a thin wall of tissue. The cells adjacent to the lumen are of three columnar epithelial cell types. Two cell types have abundant microvilli and mammalian cell-like organelle distribution and morphology. The above cell types differ in the electron density of their cytoplasms, nuclear morphologies, and organelle content. The third cell type differs from the other two in its cytoplasmic makeup. However, the most distinctive difference is the presence of large numbers of cilia at the apical surface with no evidence of microvilli. These columnar cells rest on a basal lamina adjacent to a two to three cell thick muscle layer. The entire organ is surrounded by an adventitia of unusual morphology. Histochemical investigation demonstrated that DNAase, RNAase, and protease are present in the lumen, alkaline phosphatase is associated primarily with the microvilli, small amounts of acid phosphatase are concentrated in the midcell area of the columnar epithelium, and ATPase activity is localized in the muscle cells and just below the absorptive surface of the microvillous cells. The luminal contents and adventitial areas are Sudan Black B positive, all areas of the lumen and organ wall are PAS positive, the cell nuclei and amorphous masses in the lumen showed Feulgen staining, and large vesicles in the columnar cells were Oil Red O positive. Apparently, the spermatheca of B. glabrata is both a digestive and absorptive structure. Although this organ shares functional similarities with those found in opisthobranchs and terrestrial pulmonates, the epithelia of the spermatheca differ dramatically in these groups.
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PMID:Structure and function of the spermatheca in a snail host of schistosomiasis, Biomphalaria glabrata. 364 39

Natural killer (NK) cells were obtained from C3H mouse spleens according to a modified version of the method of Kuribayashi et al. [Kuribayashi, K., Gillis, S., Dern, D. E. & Henney, C. S. (1981) J. Immunol. 126, 2321-2327]. These cells retain in vitro cytotoxicity against certain model tumor cell targets and appear homogeneous by morphological criteria. NK cells, YAC (tumor) cells, and NK cell-YAC cell conjugates have been examined with scanning (SEM) and transmission (TEM) electron microscopy. SEM experiments have shown that: (i) NK cells are large and possess various shapes in contrast to the YAC target cells which are smaller and round, (ii) YAC cells have uniformly distributed microvilli whereas the NK cell microvilli are most prominent in the area of effector-to-target contact, and (iii) in the absence of target cells, NK cell microvilli are found in a small number (usually 1-3) of cell surface locations. The region of NK cell-tumor cell contact has also been examined with TEM. The cells were stained with ruthenium red/OsO(4). The electron-dense ruthenium red/OsO(4) reaction product was consistently found in regions of close cell-cell contact, suggesting that carbohydrates were not completely cleared from areas of contact and that target and effector membranes do not fuse extensively. TEM observations indicate that NK cells have structurally unique granules. The granules are composed of at least two distinct compartments. The outer compartment contains the lysosome-associated enzymes acid phosphatase and inorganic trimetaphosphatase. No enzymatic activities have been found associated with the inner compartment. NK cells appear to degranulate when incubated with YAC cells. Under those circumstances, limited areas of the NK cytoplasm contain vacuole-like areas possessing granules and apparent granular debris. Degranulation appears to be involved in the cytotoxic function of NK cells.
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PMID:Electron microscopic study of natural killer cell-tumor cell conjugates. 629 Oct 36

This review is based on the findings of multiparameter studies performed on cells obtained from over 200 cases of leukemia and illustrates the wide range of laboratory tests currently available for cell phenotype identification. Immunological techniques are not discussed and the review deals mainly with light and electron microscopic cytochemistry, transmission (TEM) and scanning electron microscopy (SEM). The importance of light microscopic cytochemistry is clearly demonstrated. In particular, paranuclear acid phosphatase, non-specific esterase (NSE) and diaminopeptidase staining are recommended as reliable T-cell markers. Ultrastructural identification of unclassified leukemic cells using techniques to detect myeloperoxidase, acid phosphatase, platelet peroxide (PPO) and NSE, is shown to be of great importance in cases of early myelo-monoblastic differentiation with negative light microscopic cytochemistry. SEM is also shown to be a reliable means of distinguishing lymphoid and non-lymphoid leukemia when some degree of differentiation is present. However SEM does not appear to contribute in the diagnosis of unclassified leukemia. The new scanning immunoelectron microscopy (SIEM) technique employing heteroantisera or monoclonal antibodies conjugated to latex microspheres (immunolatex) to detect surface receptors and specific antigens is also illustrated. This technique displays the topography of surface antigens on the cell surface of leukemic cells in 3-dimension and facilitates simultaneous visualization of the surface architecture of the labelled cells.
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PMID:Cytochemistry and ultrastructure in lymphoma and leukemia: utility in the diagnosis of different leukemias and the recognition of subtypes of lymphoproliferative disorders. 637 13

A new giant Gram-negative non-cultivatable symbiotic endospore-forming bacterium was found in the gut of the European hamster. This "Metabacterium" sp., provisionally named "Metabacterium criceti", sp. n., has a length of approximately 20 microns and thickness of 4 microns. It forms 1 to 2 cylindrical endospores, approximately 9 microns long and 1.4 microns thick. TEM-micrographs show a cell wall structure characteristic of Gram-negative bacteria. Vegetative cells are filled with granules 0.3 micron in diameter which resemble starch granules. The reproduction occurs with binary fission and by formation of two endospores. Of thirteen biochemical components sought, four, i.e. glycogen, triacylglycerols, peroxidase and alkaline phosphatase, were not found. Starch, acid mucosubstances, DNA, RNA, lipids, proteins, adenosine triphosphatase and acid phosphatase were found in different patterns, depending on the developmental stage of the bacterium. In the vegetative cell stage all these components, with the exception of starch, were found. In the endospore-bearing cell stage, only the starch-like cell component granules could be detected. In free endospores only DNA, RNA and acid phosphatase were found. Some of the components, i.e. DNA, lipids, starch-like granules, were linked to certain cell substructures, the distribution of others, viz. polysaccharides, RNA, adenosine triphosphatase and proteins was diffuse. The lipids, found only in vegetative cells, were associated with the cell wall.
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PMID:Characterization of two Metabacterium sp. from the gut of rodents. 1. Morphology and histochemical examination of a new Metabacterium sp. from the gut of the European hamster (Cricetus cricetus) 769 4


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