Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cytoplasmic Structures”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,351 records · Page 75Linked to original sources
PubMed1985

Significance of X granules in histiocytosis X: an ultrastructural study.

Histiocytosis X is characterized by the presence of cytoplasmic rod structures called Langerhans' cell granules or X granules (XG). It has been speculated that histiocytosis X is a Langerhans' cell disorder. This ultrastructural study was performed to quantitate the number of XG containing histiocytes in the histiocytosis X lesions. Twenty-four specimens from 22 patients with histiocytosis X were studied: 4 from skin, 5 from lymph node, 11 from bone, 2 from lung, 1 from gingiva, and 1 from cheek. The majority of the histiocytes in histiocytosis X lesions do not contain X granules. The majority of the histiocytes in histiocytosis X lesions do not contain X granules. The percentage of histiocytes with XG in a lesion has no relation to the age of the patient or the organ from which it was obtained, except for skin, where they were quite numerous. The relative percent-age of histiocytes with granules does not correlate significantly with the prognosis of these patients.

Adolescent↗
PubMed2006

Nonequilibrium self-assembly of linear fibers: microscopic treatment of growth, decay, catastrophe and rescue.

Many of the large structures of cells are constructed from fibers. These fibers self-assemble from individual proteins in a far-from-equilibrium fashion. Nonequilibrium self-assembly results in a highly dynamic process at the subcellular level that can be regulated and tuned to carry out many of the biological functions of the cell: growth, division and locomotion. We construct and analyze a nonequilibrium model of the dynamic end of a biological fiber that possesses site-resolved resolution. We solve for the steady states of this nonequilibrium system using a variational method. The results are compared to exact numerical solutions for systems with modest size. Using an effective reaction coordinate, we construct an effective potential from the steady-state distribution. The stochastic transitions of the system can be analyzed in this representation. We then apply this method to model microtubule systems. Predictions for macroscopic catastrophe, rescue and dynamic instability in the steady states are analyzed. We find that the length of the cap of the microtubule is small. The relations between the catastrophe/rescue rate and the growth rate are also discussed.

Cell Physiological Phenomena↗
PubMed1962

Studies on protein uptake by isolated tumor cells. I. Electron microscopic evidence of ferritin uptake by Ehrlich ascites tumor cells.

Ferritin, added to the incubation medium of ascites tumor cells, was used as an electron microscopic marker to study the uptake of large protein molecules by morphologically intact cells. A definite uptake could be detected after 1 hour of incubation in Tyrode bicarbonate solution containing 0.04 to 13.3 mg ferritin/ml. Ferritin was found in a variety of membrane-surrounded structures, suggesting that pinocytesis and related membrane movements are occurring under physiological conditions and can account for the penetration of intact macromolecules into isolated tumor cells. Supplementation of the medium with serum albumin (33 mg/ml) increased the average amount of ferritin per cell and per pinocytotic structure. Ferritin was strongly adsorbed by fragments of lysed cells, which were readily taken up by intact cells. Besides its role as carrier, this debris appeared to stimulate membrane movements. Only rare examples were found to suggest the release of ferritin from the pinocytotic structures into the cytoplasm. Thus, the disintegration of such structures cannot be considered an obvious step towards a rapid metabolic utilization of protein by the cell. Particles of colloidal gold presented to the cell under the same conditions were not taken up to any significant extent, thus providing good evidence for a selective ingestion of particles of comparable sizes.

Animals↗
PubMed1980

Antigen-induced IgE-mediated degranulation of human basophils.

The events associated with antigen-induced, IgE-mediated degranulation of human basophils from allergic donors were studied ultrastructurally. Partially purified cells were examined prior to addition of antigen and after incubation with antigen or control buffer for 15 seconds to 60 minutes. Reactions were stopped instantaneously by adding fixative directly to the cell suspension. After fixation the cells were exposed to cationized ferritin as a sensitive probe for demonstrating possible continuities between the cytoplasmic granules and the cell surface. Ficoll-Hypaque-isolated basophils were of three types: Type I, cells containing basophil granules with a full complement of particles; type II, cells containing some full granules but also variable numbers of cytoplasmic vacuolar structures having the size and shape of basophilic granules but having reduced or no particle content (partially fixed or empty granules); and type III, basophils containing only empty granules. Following exposure to specific antigen, basophils of all three types underwent degranulation characterized by the fusion of the membranes bounding single basophilic granules with the plasma membrane and leading to extrusion of content. Cells in the process of degranulation (type IV and V basophils) were characterized by communications between individual granules and the cell exterior. Identification of such communications was facilitated by cationized ferritin which entered granules having open communications with the cell surface. Without this marker, the number of such communications would have been seriously underestimated, either because they were extremely narrow, tortuous, or outside the plane of section. The majority of individual basophilic granules fused singly and separately with the plasma membrane, in contrast to guinea pig basophil and rat mast cell degranulation where intercommunicating clusters of granules fused with the plasma membrane at a single point. The particle and membrane contents of extruded granules frequently remained adherent to the surface of type IV and V basophils and were not immediately solubilized. Morphologic evidence of degranulation progressed with time of exposure to antigen, exhibiting kinetics that paralleled histamine release. Cells in control incubations, and rare basophils that had been exposed to antigen E, failed to degranulate. Fully degranulated (type VI) basophils were viable cells that had a markedly irregular surface and were devoid of basophilic granules but retained the minor population of small perinuclear granules.

Basophils↗
PubMed1997

Prediction of invasiveness by aspiration cytology applied to nonpalpable breast carcinoma and tested in 300 cases.

In a retrospective study, fine-needle aspirates from 300 nonpalpable breast carcinomas, including 199 invasive tumors and 101 cases of ductal carcinoma in situ, were analyzed to assess the value of 11 features in predicting invasiveness in malignant breast lesions by aspiration cytology. Four findings appeared to be useful in this context: (1) malignant cell clusters with tubular structure, (2) cytoplasmic lumen formation in malignant cells, (3) fibroblast proliferation, and (4) fragments of elastoid stroma. When any combination of two or more of these key features was seen in a smear being diagnostic of malignancy, the positive predictive value regarding invasiveness was 96%. The accuracy of this prediction in terms of sensitivity and specificity was 48% and 96%, respectively. The clinical use of these observations is discussed.

Biopsy, Needle↗
PubMed2001

Ultrastructural localization of adenosine A2A receptors suggests multiple cellular sites for modulation of GABAergic neurons in rat striatum.

Activation of adenosine A2A receptors (A2AR) has been shown to antagonize the function of D2 dopaminergic regulation of striatal gamma-aminobutyric acid (GABA)-ergic output and, thus, locomotor activity. Adenosine A2A receptor immunoreactivity (A2A-LI) has been localized to rat striatum by light microscopy by using a previously characterized human A2AR monoclonal antibody. In this study, we evaluated the localization of A2A-LI and its colocalization with GABA immunoreactivity (GABA-LI) in dorsolateral rat striatum by immunoelectron microscopy to further characterize the potential mechanism of purinergic control of striatal output. Ultrastructural analysis demonstrated A2A-LI associated with the plasma membrane and cytoplasmic membranous structures of striatal neurons. A2A-LI was prevalent in dendrites and dendritic spines ( approximately 70% of total A2A-profiles counted) and less prevalent in axons and axon terminals (23%), soma (3%), and glia (3%). Cellular elements exhibiting both A2A-LI and GABA-LI comprised 23% of the total profiles counted; colabeling was most common in dendrites. A2A-LI was observed primarily at asymmetric synapses (n = 70) (both pre- and postsynaptically but predominantly in the postsynaptic element) and less frequently at symmetric synapses (n = 17). Of the 714 A2A-immunoreactive profiles examined, 37% were apposed to GABA-labeled profiles. The most common appositions were A2A-labeled dendrites apposed to GABA-immunoreactive dendrites (n = 132), axon terminals (n = 28), and somata (n = 22) and A2A-labeled axons apposed to GABA-labeled dendrites (n = 58), axon terminals (n = 14), and somata (n = 9). Our findings suggest that adenosine may play an important role in modulating excitatory input to striatal neurons and that A2AR may modulate GABAergic signaling at several cellular sites within the rat striatum.

Animals↗
PubMed1982

The ultrastructure of conventional, parosteal, and periosteal osteosarcomas.

Twenty-seven osteosarcomas of bone were examined by electron microscopy. Eighteen cases were conventional osteosarcomas, one case was an osteosarcoma that developed in Paget's disease of bone, two cases were metastasis to the lungs of conventional osteosarcomas, five were parosteal osteosarcomas (and the recurrence of one of them), and one was periosteal osteosarcoma. In addition to the basic neoplastic cell, the osteoblast-like tumor cell, seven tumor cell types could be differentiated in varying numbers in the 27 cases examined: (1) chondroblast-like; (2) fibroblast-like; (3) histiocyte-like; (4) myofibroblast; (5) osteoclast-like; (6) malignant multinucleated osteoblast-like; and (7) atypical primitive mesenchymal cells. Moreover, endothelial cells and pericytes were also present. The tumor cells showed common neoplastic features in relation with general cell configuration and fine structures. No cytoplasmic organelle was considered to be cell-specific, and only the amount and distribution of the organelles allowed us to differentiate the above mentioned cell types. The presence of malignant appearing tumor cells with abundant and dilated cisternae of RER, in an intercellular matrix containing collagen fibers with areas of focal collections or puffs of hydroxyapatite crystals, are the most characteristic ultrastructural features of osteosarcoma. However, those features are not pathognomonic and do not allow in all cases the differential diagnosis with osteoid-osteoma and benign osteoblastoma. Fields of chondroblastic, fibroblastic, or fibrohitiocytic character are indistinguishable of chondrosarcomas, fibrosarcomas, or malignant fibrous histiocytoma of bone, respectively. The comparative study of parosteal and conventional osteosarcomas revealed a marked difference in the cell population: fibroblast-like cells and myofibroblasts were the main cell types in parosteal osteosarcoma; on the contrary, myofibroblasts were very scarce or absent in conventional osteosarcomas. This difference may correlate with the better outcome of parosteal osteosarcoma. The ultrastructural features of a periosteal osteosarcoma are reported for the first time. The tumor was comprised mostly of chondroblast-like tumor cells. However, in the more cellular peripheric areas of the neoplasm, the cells were predominantly of the fibroblast-like type and showed anaplastic features.

Bone Neoplasms↗
PubMed1984

Medullomyoblastoma. A histologic, immunohistochemical, and ultrastructural study.

The light and electron microscopic features of a medullomyoblastoma arising in the cerebellar vermis of a 3-year-old boy are described. Differentiation along both glial and neuronal lines was present in the medulloblastoma component of the tumor. Astrocytic differentiation was confirmed by the observation of compact bundles of 8 to 10 nm glial filaments in cellular processes on ultrastructural examination, and by positive immunostaining for glial fibrillary acidic protein (GFAP). Neuroblastic differentiation was suggested by the demonstration of axon-like processes on silver impregnation, and ultrastructurally by the observation of microtubules, dense-core and clear vesicles, and rare synapse-like structures within cytoplasmic processes. The presence of both primitive and well-differentiated striated muscle fibers in the tumor was confirmed by the demonstration of thick and thin myofilaments and Z bands on electron microscopy, and by positive immunostaining for myoglobin. These findings clearly establish the presence of both neuroectodermal and rhabdomyoblastic components in this neoplasm, and thus set it apart from the pure rhabdomyosarcomas, which may also occur in the cerebellar vermis in children. This case also illustrates the usefulness of electron microscopy and immunohistochemistry in the diagnosis and histogenetic evaluation of primitive or poorly differentiated small cell tumors of the central nervous system.

Cerebellar Neoplasms↗
PubMed1995

Subcellular organization of calcium signalling in hepatocytes and the intact liver.

Hepatocytes respond to inositol 1,4,5-trisphosphate (InsP3)-linked agonists with frequency-modulated oscillations in the intracellular free calcium concentration ([Ca2+]i), that occur as waves propagating from a specific origin within each cell. The subcellular distribution and functional organization of InsP3-sensitive Ca2+ pools has been investigated, in both intact and permeabilized cells, by fluorescence imaging of dyes which can be used to monitor luminal Ca2+ content and InsP3-activated ion permeability in a spatially resolved manner. The Ca2+ stores behave as a luminally continuous system distributed throughout the cytoplasm. The structure of the stores, an important determinant of their function, is controlled by the cytoskeleton and can be modulated in a guanine nucleotide-dependent manner. The nuclear matrix is devoid of Ca2+ stores, but Ca2+ waves in the intact cell propagate through this compartment. The organization of [Ca2+]i signals has also been investigated in the perfused liver. Frequency-modulated [Ca2+]i oscillations are still observed at the single cell level, with similar properties to those in the isolated hepatocyte. The [Ca2+]i oscillations propagate between cells in the intact liver, leading to the synchronization of [Ca2+]i signals across part or all of each hepatic lobule.

Animals↗
PubMed2006

Tryptamine induces cell death with ultrastructural features of autophagy in neurons and glia: Possible relevance for neurodegenerative disorders.

Tryptamine derivatives are a family of biogenic amines that have been suggested to be modulators of brain function at physiological concentrations. However, pharmacological concentrations of these amines display amphetamine-like properties, and they seem to play a role in brain disorders. Amphetamines induce autophagy in nerve cells, and this type of cell death has also been involved in neurodegenerative diseases. In the present work, we clearly demonstrate for the very first time that high concentrations of tryptamine (0.1-1 mM) induce autophagy in HT22 and SK-N-SH nerve cell lines and in primary cultures of astrocytes, glial cells being less sensitive than neurons. Ultrastructural cell morphology shows all of the typical hallmarks of autophagy. There is no nuclear chromatin condensation, endoplasmic reticulum and mitochondria are swollen, and a great number of double-membraned autophagosomes and residual bodies can be shown in the cytoplasm. Autophagosomes and residual bodies contain mitochondria, membranes, and vesicles and remain unabridged until the cell membrane is disrupted and the cell dies. The same results have been found when cells were incubated with high concentrations of 5-methoxytryptamine (0.1-1 mM). Our results establish a possible link between the role of tryptamine derivatives in brain disorders and the presence of autophagic cell death in these kinds of disorders.

Animals↗
PubMed2002

Cytologic features of alveolar soft part sarcoma: report of three cases.

Alveolar soft part sarcoma (ASPS) is a rare, high-grade, epithelial-like sarcoma that shows characteristic histopathologic findings. Although a chromosomal anomaly that seems specific has been recently described, its diagnosis is based on histologic and ultrastructural features. The tumor shows no specific immunohistologic findings. Cytologic features of three cases of ASPS are presented. Preoperative fine-needle aspiration (FNA) of the primary soft tissue tumor was performed in two cases. In another two, mediastinal and pulmonary and subcutaneous metastatic lesions were aspirated. In all cases the cytologic image was identical with numerous, dissociated, large neoplastic cells with round-to-plasmocytoid morphology. Cytoplasmic fragility and granularity with abundant, atypical, naked nuclei were present. In one case, FNA material was available for ultrastructural studies. It disclosed the characteristic cytoplasmic crystalline structures. A specific cytologic diagnosis of ASPS was given in all cases. In conclusion, ASPS is a rare neoplastic entity that shows a characteristic cytologic image. When accompanied by an adequate clinical context it permits specific preoperative recognition. While immunocytologic studies are helpful to exclude other neoplasms, ultrastructure may result in an exact diagnosis.

Adult↗
PubMed1996

Hepatitis C virus: detection of intracellular virus particles by electron microscopy.

We previously demonstrated that a human T-cell line, HPBMa10-2 derived from HPBALL, was capable of supporting a productive infection of hepatitis C virus (HCV). We subsequently found Daudi cells, a human B-cell line, to be susceptible to HCV infection. Employing these cell lines infected with HCV as well as liver obtained during the acute phase of hepatitis C from a chimpanzee, we observed intracellular HCV particles by electron microscopy (EM). We detected viruslike particles with a diameter of approximately 50 nm in the cytoplasmic vesicles. In Daudi cells harvested 15 days after virus inoculation, the appearance of cytoplasmic tubular structures which we originally described for chimpanzee hepatocytes in association with HCV infection was noted. Immunoperoxidase EM using antibodies against HCV core and envelope demonstrated that the particles contained the viral antigens.

Animals↗
PubMed1991

Kinetics of the osteoclast cytoskeleton during the resorption cycle in vitro.

Resorption and migration phases alternate in the life of the osteoclast. We have previously described a specific microfilament structure at the attachment sites in resorbing osteoclasts. In the present study we have examined microfilaments and microtubules in both resorbing and migrating rat osteoclasts cultured on bone slices. In migrating osteoclasts microfilaments form so-called podosome structures containing vinculin, talin, and F-actin at the paramarginal area of the cell. When the osteoclast prepares itself for resorption, the podosomes gather to a certain area and form a broad ring around the area, which is then resorbed. In the resorbing osteoclast, vinculin and talin form a continuous double circle, which may be partially formed by podosomes, and between these double circles a broad zone is formed by F-actin. Narrow vinculin and F-actin rings were found in osteoclasts at the end of the resorption phase. The different configurations of microfilaments in 1 and 2 day cultures were correlated in terms of their relationship to the resorption lacunae. The vitamin A derivative isotretinoin significantly stimulated resorption and increased the number of microfilament configurations associated with the resorption pits. On the other hand, Bt2cAMP abolished resorption and prevented the formation of a specific ring structure of microfilaments. Based on these data, a kinetic model of the whole migration-resorption cycle of the osteoclast cultured on the bone slice is presented. With alpha-tubulin stainings of microtubules two different cytoskeletal organizations were observed. In migrating osteoclasts, microtubules were evenly distributed over the whole cell. In the resorbing osteoclast, there was a noticeable concentration of these cytoskeletal structures at cytoplasmic sites closest to the resorption lacuna. This orientation of microtubules may reflect the active secretory function of the resorbing osteoclast.

Actin Cytoskeleton↗
PubMed2001

Immunocytochemical and electrophoretic distribution of cytokeratins in the resting stage epidermis of the lizard Podarcis sicula.

The distribution of three anti-cytokeratin (alpha-keratin) antibodies (AE1, AE2, AE3) in the epidermis of a lizard has been studied by immunocytochemistry at light and electron microscope and by immunoblot analysis. This study shows the expression of different keratins in the resting stage epidermis of the lizard Podarcis sicula. In this stage the epidermis has an external beta-layer, an underlying alpha-layer, some layers of living suprabasal cells and a basal stratum germinativum. The AE1 antibody is localized in the basal and suprabasal cells only in the outer scale surface, but is absent from the inner surface, the hinge region and from the keratinized beta- and alpha-layers. The AE2 antibody is mainly localized at the level of the hinge region and of the alpha-layer and gives a lower reaction in the beta-layer. The AE3 antibody is mainly localized in basal and suprabasal cells, lower in the alpha-layer, and absent from the beta-layer. The electron microscope shows that all the three antibodies immunolabel cytoplasmic fibrillar structures in the deep alpha-layers and that AE2 and AE3 antibodies label small electron-dense areas in the external dense beta-layer within the electron-lucid matrix. Immunoblot analysis of the keratins extracted and separated by gel electrophoresis demonstrates the presence of a band of high molecular weight (67-68 kDa) positive to all three antibodies. In addition AE1 antibody recognizes a 44-45 kDa band and a 57-58 kDa band, AE2 recognizes a 60-61 kDa band, and AE3 recognizes a 47 kDa and a 56-57 kDa band. The localization of the keratins identified by immunoblot analysis in the epithelial layers is discussed taking in account the immunolabeling at light and electron microscope. The present study suggests that also in the normal epidermis of this reptiles, in both the alpha- and the beta-layer, the molecular masses of keratins increase from the basal to the keratinized layers, a phenomenon which is generalized to adult and embryonic amniotes epidermis.

Animals↗
PubMed1981

Biochemical studies of mammalian oogenesis: kinetics of accumulation of total and poly(A)-containing RNA during growth of the mouse oocyte.

Kinetics of accumulation of total and poly(A)-containing RNA have been measured during growth of the mouse oocyte. Total RNA from oocytes isolated at discrete stages of growth was determined by two independent microassays. The full-grown oocyte contained about 0.60 ng of RNA. Kinetics of accumulation of total RNA with respect to oocyte volume were biphasic. Small, growing oocytes (about 30 pl) contained about 0.20 ng of RNA/oocyte. The amount of RNA increased in a quasi-linear fashion until oocyte volume was about 160 pl, at which point there was about 0.57 ng of RNA/oocyte. Thus oocytes about 65% of their final volume had accumulated about 95% of the total amount of RNA present in the fully-grown oocyte. The relative amount of poly (A)-containing RNA in oocytes of various size was determined by in situ hybridization of [3H] poly (U) to ovarian sections from juvenile mice of known age, followed by autoradiography. The kinetics of accumulation of poly (A)-containing RNA were similar to those of total RNA; oocytes about 70% of their final volume had accumulated about 95% of the amount of poly (A)-containing RNA present in the fully-grown oocyte. The poly(A)-containing RNA resided predominantly in the cytoplasm and no obvious cytoplasmic localization was observed. Kinetics of accumulation of total RNA, which is mainly ribosomal, and poly (A)-containing RNA were consistent with levels of RNA polymerases I and II measured by others during oocyte growth (Moore and Lintern-Moore, '78). The number of ribosomes that could be made from the amount of rRNA present at various stages of growth was compared to the actual number of ribosomes calculated from a published morphometric study (Garcia et al., '79). Kinetic differences in accumulation between the theoretical and actual number of ribosomes suggested oocyte ribosomes are recruited into cytoplasmic lattice structures. These structures accumulate during oocyte growth and have been postulated to be a ribosomal storage form. In addition, the results from this study are compared to results derived from lower species.

Animals↗
PubMed2005

Ultrastructure of testicular macrophages in aging mice.

Testicular macrophages of aging mice were studied by TEM. Testicular macrophages retained with Leydig cells the close morphological relationships observed in the adult young animals, but digitations were not found. Lipofuscin granules like those of the Leydig cells from aging mice were observed in the cytoplasm. These organelles were generally absent in the testicular macrophages of young adult mice. Testicular macrophages did not display phagocytosis of the lipofuscin granules. In addition, the latter were not found in the intercellular spaces. These observations indicated that lipofuscin granules were formed, at least in a great part, within testicular macrophages as a consequence of metabolic changes occurring with age. Fine lamellar organization was seen in the lipofuscin granules of both Leydig cells and testicular macrophages. Frequently, lipofuscin granules originated from secondary lysosomes containing lipidic vacuoles only. Together with accumulation of the lipofuscin granules, changes of testicular macrophage fine morphology were observed. Endoplasmic reticulum and Golgi apparatus became poorly developed, and coated vesicles were rarely found. Fewer mitochondria were encountered, but their ultrastructure was not altered. These results suggest that in testicular macrophages lipofuscin accumulation is associated with a functional involution.

Aging↗