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

The water-rich phase (tissue channels) of the intersititial tissue in rat ileum, knee joint capsules, kidneys, and implanted Guyton's capsules was examined electron microscopically by the SEM of plastic injection models, and by TEM and HVEM of ferrocyanide and ferritin as tracers. It was shown that the channels do in fact exist, and are not just vacuoles. Quantitative estimations of their numbers and diameters were made. These agreed well with estimates made by other methods.
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PMID:The quantitative morphology of interstitial tissue channels in some tissues of the rat and rabbit. 72 12

Scanning and transmission electron microscopy (SEM and TEM) revealed unique structures and development of the venomous spicules of tussock moth caterpillars of the genus Euproctis: (1) Flower-like structure at the distal end and a longitudinal minute depression on the proximal subapical wall of these spicules were observed by SEM. This depression was revealed to be a small hole by TEM. (2) During molting, observed were cytoplasmic processes of several trichogen cells penetrating the cytoplasm of a tormogen cell to form the spicules with the holes at their subapical portions. A papilla was formed by a tormogen and several epidermal cells. (3) After the molting, the cytoplasmic process in a spicule disappeared and the spicule cavity was replaced by electron-dense materials secreted apparently from the trichogen cell. (4) It was considered that the electron-dense materials were the main toxic or precursory substances in the Euproctis spicules.
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PMID:Studies on the venomous spicules and spines of moth caterpillars. I. Fine structure and development of the venomous spicules of the Euproctis caterpillars. 73 32

Aggregations of isolated embryonic and adult heart cells were studied so as to examine in detail the formation of cell contacts, the assembly of cells into multicellular systems, and cell co-operation in forming organized and differentiating tissues. At selected intervals after initiating rotation cultures, aggregates were examined microscopically for evidence of contractility, and subsequently processed for scanning and transmission electron microscopy (TEM, SEM). By continuous accretion of single cells, and the joining of small clusters, the aggregates increased in size. Cells within the aggregates exhibited rhythmic and synchronous contractility by 3--12 h of culture, suggesting the formation of low-resistance inter-cellular junctions between apposed cells. Two populations of cells could be recognized by 9--12 h with SEM. One was spherical in surface view and the other was flattened. Spherical cells possessed myofibrils, and were classified as cardiac myocytes which occupied the core of the aggregate. The flattened cells were devoid of myofibrils and non-muscle in nature. They covered the surface in a multilayered epithelium. At 12h the aggregates were round to oval, covered by flattened cells, but individual round cells could still be recognized. Intercalated discs were frequently observed in 12 h aggregates. The junctional complexes observed in 12--72 h aggregates include desmosomes, fascia adherens and gap junctions. Most of the aggregation was completed by 24 h, and at later time periods, i.e. 48--72 h, the external surface of the aggregates was smoothed out with epithelial investment. In these aggregates myofibrils and intercellular junctions became reconstructed in less than 24 h. Unlike embryonic myocardial cells, adult cells did not form aggregates of numerous cells. Instead, they formed irregular clusters of 2--5 cells during 3--48 h of culture. Intercellular contacts and suggestive desmosomal materials were observed between adherent cardiac muscle cells. When culture continued for 48--72 h, the cells underwent supercontraction and became non-viable, suggesting that the terminally differentiated adult myocardial cells are incapable of regenerating constituents obligatory for histogenetic reconstruction.
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PMID:Reconstruction of mammalian heart tissue from embryonic heart cell suspension with reference to the aggregation of adult heart cells. 75 14

Scanning (SEM) and transmission (TEM) electron microscopy were used to elucidate morphological changes associated with acute tubular necrosis induced by high doses of mercuric chloride. Marked morphological changes were demonstrated in proximal tubules with TEM at one hour and with both SEM and TEM at six hours. These changes appeared earlier than reported in previous studies using any dose. The scanning microscopic provided a three-dimensional view of proximal cells showing changes in early injury with subsequent separation of the injured cells from the remaining cells. Certain of these residual cells change into low-lying cells with reline the proximal tubule. Variability was seen in the number of residual cells. However, once cell injury was initiated, necrosis proceeded in a reproducible manner.
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PMID:Scanning and transmission electron microscopy of mercuric chloride-induced acute tubular necrosis in rat kidney. 80 31

A combined scanning/transmission electron microscopic (SEM/TEM) technique was used to analyze the third cerebral ventricle and underlying tissue of the median eminence of 6 mature rhesus monkeys. The same sample of the ventricular wall was subjected to both SEM and TEM. This technique demonstrates two basic subpopulations of supraependymal cells on the surface of the supraoptic, infundibular and mammillary recesses. Type 1 cells are definitely neuron-like in their surface configuration and internal fine structural organization. Type 2 cells are more similar to histiocytes and are not as numerous as type 1 cells. The functional capacity of type 1 cells is discussed in the context of their potential role as a neuronal network that may serve as a short loop autoregulatory mechanism controlling the synthesis of releasing hormones or biogenic amines.
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PMID:The primate median eminence. I. Correlative scanning-transmission electron microscopy. 80 41

Fine structural alterations of liver sinusoids in young and adult albino rats breathing 6% oxygen in nitrogen at normal atmospheric pressure for periods from 3 to 30 h were described by use of TEM and SEM. After short-term hypoxia the fenestrated areas of endothelial cells were partially destroyed. After long--term hypoxia wide gaps could be visualized in the endothelium, too. In the liver specimens of all hypoxic animals electron lucent membrane bounded blebs arose from the endothelial lining. Cytoplasmic protrusions of hepatocytes bulged into the sinusoidal lumen. In the space of Disse and the sinusoidal lumen bleblike corpuscles and parts of cytoplasmic membrane being discharged from liver cell vacuoles could be observed. The find structure of liver sinusoids in hypoxia was very similar in young and adult albino rats. The findings suggest a discharge of metabolites and cellular components from endothelial cells and hepatocytes in a state of energetic insufficiency by forming cellular blebs and protrusions. It was supposed, that the combined effects of hypoxia and shearing of circulating blood were responsible for the development of holes and gaps in the endothelial lining.
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PMID:[On the influence of hypoxia on the sinus endothelial cells of rat liver. A scanning and transmission electron microscopic investigation (author's transl)]. 82 Dec 46

The fixation of rat liver by perfusion with glutaraldehyde with different pressures has been investigated. For this study adult male albino rats were used. Rat livers were fixed by perfusion through the abdominal aorta according to the method of FORSSMANN et al. (1967). Perfusion pressures varied from 30 to 210 mmHg. A continuous complete endothelial lining of liver sinusoids could be visualized with TEM and SEM after fixation with perfusion pressures lower than 100 mmHg. Three different regions could be noticed in the endothelial cell: 1. prominent nucleous region, 2. compact cytoplasmic processions containing mitochondria and ergastoplasma, 3. delicate fenestrated cytoplasmic areals. As a rule the fenestrations were localized in groups, s.c. sieve plates. After perfusion fixation with pressures above 100 mmHg the endothelial lining of liver sinusoids appeared similar to a wide-meshed net. The sieve plates were destroyed, and numerous defects could be found in the endothelial cells. Hepatocytes showed vacuoles which seem to be due to invagination of the cellular membrane. For the development of artifacts even with physiological perfusion pressures in the aorta (110 mmHg), the content of procaine in the rinsing solution is responsible. Eliminating the function of arteriols leads to unphysiological pressure effects in the sinusoids.
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PMID:[The fine structure of liver sinusoids after perfusion fixation with various pressures. A transmission and scanning electron microscopic study (author's transl)]. 82 39

Studies with transmission and scanning electron microscopes (TEM and SEM) were performed on specimens from patients suspected of leukemic reticuloendotheliosis (LRE), irrespective of the final diagnoses. The blood samples were fixed immediately in order to avoid in vitro changes of leukocytes. Leukemic reticuloendotheliosis cells demonstrated numerous long microvilli and pseudopods, whereas the immediately fixed lymphocytes demonstrated fewer, shorter microvilli and no pseudopods. These surface features distinguishing LRE cells from lymphocytes and monocytes were appreciated by both SEM and TEM. In addition, TEM revealed significant differences in the incidence of certain ultrastructural alterations. Whereas nuclear pockets were rare in lre cells, they were relatively frequent in lymphocytes of other hematologic disorders. The inclusions of ribosome-lamella complexes were not only more prevalent in patients with LRE but were seen in a higher percentage of leukemic cells from patients with LRE than in those from patients with other hematologic disorders. Electron microscopy can play a role in the laboratory diagnosis of LRE.
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PMID:Further ultrastructural characterization of hairy cells of leukemic reticuloendotheliosis. 83 14

Samples of human semen frozen in liquid nitrogen ( - 196 degrees C) with no glycerol, 5 and 10% glycerol were compared with samples that were untreated, with 10% glycerol but not frozen, and spermatozoa frozen at -20 degrees C. SEM and TEM of the samples indicates that 10% glycerol caused fewer surface changes of the spermatozoa than other treatments. Motility counts after the various freezing treatments were also highest when 10% glycerol was used as the cryoprotectant. Nonetheless, cryopreservation is detrimental to spermatozoa and often causes considerable damage to the acrosome with a leakage of the acrosomal contents.
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PMID:Surface structure of spermatozoa frozen for artificial insemination. 88 75

The peripheral blood cells of a patient with acute plasma cell leukemia were examined with transmission (TEM) and scanning (SEM) electron microscopes. The TEM features of the immature plasma cells comprised lobulated and irregulary shaped nuclei, with scanty heterochromating and bizarre nucleoli, parallel arrays of endoplasmic reticulum, cytoplasmic fibrils and numerous polymorphic mitochondria. SEM examination of the cells showed long, thin irregular ruffles, or round blebs on the cell surface, with appearance different from this observed on other types of leukemia. A remarkable clinical and hematological remission was achieved with administration of melphalan and steroids.
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PMID:Transmission and scanning electron microscopy study on plasma cell leukemia. 89 Jan 42


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