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

The bone marrow of a patient with multiple myeloma of the IgG2 Kappa type with spontaneously crystallizing cryoglobulin was studied by electron microscopy. The ultrastructure of the myeloma cells disclosed the presence of a crystalline material in the cytoplasm within the rough endoplasmic reticulum (RER) as well as in extracisternal sites. The crystalline material was also seen extracellulary with a distinctly unique subunit structure. The tubular units measured 200 +/- A (SEM) externally with an internal diameter of 100 +/- A (SEM). The intracellular distribution did not indicate a characteristic organelle association usually observed in protein synthesizing cells. It is suggested, based on the present observations and the findings of others, that the crystalline material may represent polymerized protein synthesized by free ribosomes mostly in extracisternal locations, a pattern often seen in neoplastic plasma cells. Diffusion to extracisternal sites of precrystalline material through the membranes of the RER is a possible alternative mechanism.
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PMID:Ultrastructure of myeloma cells in a case with crystalcryoglobulinemia. 40 21

A supraependymal cluster of neuronal cells and processes consistently present on the floor of the hamster third ventricle was identified and characterized by means of correlative scanning (SEM) and transmission (TEM) electron microscopy. SEM revealed each cluster to be ovoid with the majority of its surface covered by dome-shaped protrusions and fine beaded fibers. A number of processes traveling individually or in groups also entered or exited from the cluster at its base. As these processes passed over the ventricular surface, they contributed to an extensive network on the floor and ventral aspect of the ventricular wall. Some processes terminated on the ependymal surface in bulbous endings while others penetrated the ependyma. The neuronal nature of these clusters and their associated processes was confirmed at the TEM level. The dome-shaped protrusions visible on the surface of the cluster in SEM corresponded to apical surfaces of neurons confined to the peripheral aspect of a core of loosely arranged processes. These cells exhibited a prominent nucleolus, stacks of rough endoplasmic reticulum (RER), polyribosomes, Golgi cisternae, mitochondria and microtubules (MT) and gave rise to dendritic processes which extended into the core. These dendrites gave off branches at acute angles and contained polyribosomes, single cisternae of RER and evenly spaced MT. Other profiles of processes within the core shared these characteristics, suggesting that they also were branches of the peripheral cells. Axons present within the core and on the cluster's surface exhibited vesicle-filled varicosities which frequently established synaptic contact with the peripheral cells and their processes. The presence of an intraventricular cluster of neurons which potentially communicates with centers extrinsic to the ventricle may have important implications in the hypothesized role of cerebrospinal fluid and tanycytic ependyma in the neuroendocrine regulation of anterior pituitary function.
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PMID:Electron microscopic demonstration of a supraependymal cluster of neuronal cells and processes in the hamster third ventricle. 64 88

As observed by SEM, the repair of an ovulated mammalian follicle is accompanied by a sequence of morphogenetic processes. In the initial phase, a mass of cells and coagulated fluids forms at the site of rupture. Shortly thereafter, connective cells, recruited from the adjacent and subjacent connective tissue stroma begin to proliferate and to migrate over this mass such that in the rabbit, the entire site of disruption is covered by a layer of connective cells by approximately 2 days following ovulation. Coincident with the migration of the connective tissue, superficial cells from undisturbed lateral and basal areas of an ovulated follicle also proliferate and begin to migrate over the newly established connective tissue matrix. By approximately 4 days following ovulation in the rabbit, the surface of an ovulated follicle is repopulated by elements of the superficial epithelium. The formation of the underlying corpus luteum (corpora lutea) involves characteristic morphological changes as granulosa cells transform into steroid secreting luteal cells. The luteal cells become organized into cords of cells which usually surround capillary vessels. When examined by SEM, the smooth-surfaced endoplasmic reticulum of the luteal cell is quite apparent and is observed to form a three-dimension network of anastomosing tubules which are continuous with the nuclear membrane. Variations in the appearance of the surface of the ovary which directly overlies corpora lutea were observed when the mouse, rat and rabbit were compared. The regression of corpora lutea involves the infiltration of the luteal mass by connective tissue and both degeneration and vacuolization of the luteal cells. The regressing corpus luteum is a honey-comb-like structure in which each space is occupied by a degenerating luteal cell.
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PMID:A scanning electron microscopic study of the luteo-follicular complex. III. Repair of ovulated follicle and the formation of the corpus luteum. 66 7

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

The effects of temporary vascular occlusion with surgical clips on the underlying endothelial lining were studied with scanning (SEM) and transmission (TEM) electron microscopy. Twenty-five rabbits were anesthetized and both common carotid arteries exposed. A Heifetz clip was used to occlude the right carotid artery for 5, 15, and 30 minutes, and 2 hours in five animals each. The clips were removed and the vessels immediately perfused with glutaraldehyde. In five remaining animals, the right carotid arteries were occluded for 30 minutes followed by removal of the clip and resumption of blood flow for 30 minutes prior to fixation. Combined SEM and TEM examination of the endothelium of compressed segments revealed "craters" and "balloons", blebs and vacuoles, swollen mitochondria, dilated granular endoplasmic reticulum, and subendothelial edema. There were also areas of endothelial cell flattening, discontinuity, and desquamation exposing the subendothelial tissues. Following restoration of flow, platelets and fibrin were found adherent to altered endothelial cells and to exposed subendothelial tissues. Endothelial craters and balloons were also found distal and, significantly less frequently, proximal to the site of occlusion. It is suggested that antiplatelet aggregating agents may prove beneficial for the prevention of thrombus formation at the site of the clip as well as craters and balloons distal to the clip following procedures requiring temporary vascular occlusion.
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PMID:Endothelial cell damage by temporary arterial occlusion with surgical clips. Study of the clip site by scanning and transmission electron microscopy. 97 35

The lymphocytes and antigen presenting cells in lymph node of rats stimulated by He-Ne laser acupuncture were observed by using TEM and SEM to investigate the ultrastructural changes of them. There were numerous activated T-cells which showed deeply indented nucleus, abundant small void mitochondria and free ribosomes in the paracortex area. The B-cells were gradually differentiated into large lymphocytes, immature and mature plasmatic cells which with a lot of rough endoplasmic reticulum. They were prominently increased in the pulp area. The macrophages had short processes with numerous folds and microvilli and tended to neighboring lymphocytes. The nucleus pores were increased. There were a lot of pinocytosomes, phagosomes, lysosomes in various size of macrophages. The bundles (5-6 nm in diameter) of microfilaments of the macrophages were extended from the cytoplasm to the processes. The interdigitating cells which contained the characterized single layer of rER, numerous polysomes, mitochondria and well-developed Golgi-complex were closed to macrophages and lymphocytes. In conclusion the activities of the cellular immunity and humoral immunity were enhanced by laser.
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PMID:[Effect of He-Ne laser acupuncture on lymph-nodes in rats]. 139 58

The present study employs transmission (TEM) and high-resolution scanning electron microscopy (HR-SEM) to examine the inter- and intra-cellular organization of the pars distalis of the chicken anterior pituitary gland. The overall view of the cryofractured surface of the par distalis illustrates the arrangement of different pituitary cells and tissues in the follicles. Fine structural examination by HR-SEM shows that the membrane of the mitochondria has a similar configuration to that of the rough endoplasmic reticulum. Granule-like structures, on the surface of the mitochondrial membrane, are similar in size to ribosomes. Standard imaging and three-dimensional imaging demonstrated the formation of developing granules inside the Golgi sacs and the release of mature granules from the end of Golgi stacks. The occurrence of granule-granule connections suggests that granules may be released by exocytosis in groups or individually.
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PMID:Correlative transmission electron microscopy and high resolution scanning electron microscopy studies on the fine structural organization of the chicken pituitary gland. 162 46

The epithelial cell types present in respiratory (= distal alveolarized) and terminal (= distal nonalveolarized) bronchioles in adult human lung were characterized with scanning and transmission electron microscopy (SEM, TEM) and light microscopic cytochemistry, using specific antibodies against surfactant protein SP-A and mucins, and Alcian blue/periodic acid-Schiff (AB/PAS) staining. In the respiratory bronchiole, two epithelial cell populations share the same basal lamina: one pseudostratified columnar with ciliated, secretory, and basal cells and the other predominantly simple cuboid with some interspersed flat (type I) cells. The columnar secretory cells show the ultrastructure of mucous cells. Light microscopically, they react with mucin antibodies and contain primarily periodate-reactive acid mucins. The mucous cells are the distal secretory cells described by Clara (1937). The cuboid cells are identified as type II (precursor) cells based on ultrastructural criteria for embryonic type II cells (Ten Have-Opbroek et al., 1988a, 1990a), including a cuboid cell shape, a large and roundish nucleus, rough and smooth endoplasmic reticulum (ER), osmiophilic multivesicular bodies, and dense bodies. These dense bodies in turn frequently exhibit--like those in embryonic type II cells--internal vesicles or lamellae, variability in size and shape, a specific relationship to ER and a widespread cytoplasmic distribution. Finally, the cuboid cells show a cytoplasmic staining pattern for SP-A. The terminal bronchiole is lined by the columnar cell population. In the respiratory bronchiole, the columnar (bronchial) and cuboid (alveolar) cell populations occupy distinctly different zones (pulmonary artery zone versus remaining wall). The alveolar part of the respiratory bronchiole (called alveolar tubule) defines the proximal border of a true respiratory unit.
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PMID:The proximal border of the human respiratory unit, as shown by scanning and transmission electron microscopy and light microscopical cytochemistry. 170 49

Honey bee photoreceptors contain large sacs of endoplasmic reticulum (ER) that can be located unequivocally in freeze-dried cryosections. The elemental composition of the ER was determined by electron probe x-ray microanalysis and was visualized in high-resolution x-ray maps. In the ER of dark-adapted photoreceptors, the Ca concentration was 47.5 +/- 1.1 mmol/kg (dry weight) (mean +/- SEM). During a 3-sec nonsaturating light stimulus, approximately 50% of the Ca content was released from the ER. Light stimulation also caused a highly significant increase in the Mg content of the ER; the ratio of Mg uptake to Ca released was approximately 0.7. Our results show unambiguously that the ER is the source of Ca2+ release during cell stimulation and suggest that Mg2+ can nearly balance the charge movement of Ca2+.
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PMID:Electron probe microanalysis of calcium release and magnesium uptake by endoplasmic reticulum in bee photoreceptors. 199 66

The present study was carried out to determine whether the major steroidogenic organelles of luteal cells quantitatively reflect variations in ovarian steroid secretion rates during pregnancy in the rat. Assessments were made on day 16 and in the morning (AM) and afternoon (PM) of day 22 (term is day 23). Ovarian steroidogenesis differs both quantitatively and qualitatively between these stages of pregnancy, so together they provide an ideal physiological model to study structural-functional relationships in the ovary. Corpora lutea of five rats were examined at each stage after progesterone and 20 alpha-hydroxypregn-4-en-3-one (20 alpha-OHP) secretion rates had been determined by a venous outflow technique. Total progestin secretion (progesterone plus 20 alpha-OHP) fell from 32.5 +/- 5.2 to 9.8 +/- 1.2 micrograms/hr per ovary (mean +/- SEM) between day 16 and day 22 AM but then increased to 22.6 +/- 1.4 micrograms/hr per ovary by day 22 PM. The total volume of luteal cell cytoplasm was slightly greater at day 22 AM and PM than at day 16. Similarly, the volumes of smooth endoplasmic reticulum (SER), lipid droplets, and membrane-bound granules all increased, but the volume of mitochondria decreased slightly. In contrast, the surface areas of SER and the inner and outer mitochondrial membranes did not change between day 16 and day 22 AM but then increased substantially by day 22 PM. Therefore, steroid secretion rates per unit area of steroidogenic membrane showed no consistent pattern over the stages examined.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Quantitative changes in steroidogenic organelles in the corpus luteum of the pregnant rat in relation to progestin secretion on day 16 and in the morning and afternoon of day 22. 204 55


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