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 397 records · Page 22Linked to original sources
PubMed1979

Intermediate-sized filaments present in Sertoli cells are of the vimentin type.

The cytoplasmic structure of Sertoli cells of rat testes has been studied by electron microscopy of ultrathin sections. Sertoli cells contain numerous intermediate-sized (7-11 nm) filaments which form a meshwork extending throughout the whole cytoplasm. Often the frequency of such filaments appears especially high in juxtanuclear and cortical regions, including the apical recesses containing the spermatids. Examination of frozen sections of testes by indirect immunofluorescence microscopy using guinea pig antibodies to prekeratin and vimentin has shown the absence of intermediate-sized filaments of the cytokeratin type in all cells of the testes but the presence of filaments of the vimentin type in Sertoli cells as well as in cells of the interstitial space. These results show that the intermediate-sized filaments, abundant in Sertoli cells, are of the vimentin type. In addition we conclude that the "germ epithelium" differs from others true epithelia by the absence of cytokeratin filaments and typical desmosomes and, in Sertoli cells, the presence of vimentin filaments, suggestive of a mesenchymal character or derivation.

Animals↗
PubMed1987

[Morphological changes in the filtration-reabsorption barrier of the remaining kidney after its denervation and disordered lymph outflow].

An electron microscopical investigation on combined effect of denervation and disturbance of lymphatic outflow to structural elements of the FRB in the preserved kidney after contralateral nephrectomy has been performed on 20 mature white rats in 3, 30, 180, 360 days. In 3 days in the cellular components of the FRB cytoplasmic structures are at the state of functional strain and overstrain. Hemostasis is observed in glomeruli and in peritubular capillaries, as well as edema of the interstitial connective tissue. In 30 days certain signs of hyperplasia and hypertrophy of intracellular structures appear in the components of the FRB. However, later (in 180, 360 days) certain tendency to predominance of processes of functional strain in the intracellular structures with their certain destruction and reaction of the connective stroma is observed.

Absorption↗
PubMed1981

Hepatocyte differentiation during early fetal development in the rat.

Rat hepatocyte differentiation between day 12 and 19 of fetal life was studied by electron microscopy. The cytoplasmic structures involved in synthetic and secretory function, i.e., rough endoplasmic reticulum and Golgi apparatus, appear to be the first to differentiate, and their development is probably related to the secretion of different kinds of plasma proteins. The cytoplasmic organelles involved in other hepatic functions develop later: lysosomes from day 15, peroxysomes, glycogen rosettes and smooth endoplasmic reticulum still later. However, the morphological differentiation of bile canaliculi begins from day 12.

Animals↗
PubMed2005

Reduced expression of the rotavirus NSP5 gene has a pleiotropic effect on virus replication.

Rotavirus RRV gene 11 encodes two non-structural proteins, NSP5 and NSP6. NSP5 is a phosphorylated non-structural protein that binds single- and double-stranded RNA in a non-specific manner. Transient expression of this protein in uninfected cells has provided evidence for its participation in the formation of electron-dense cytoplasmic structures, known as viroplasms, which are thought to be key structures for the replication of the virus. NSP6 is a protein of unknown function that seems not to be essential for virus replication in cell culture. To study the function of NSP5 in the context of a viral infection, the expression of RRV gene 11 was silenced by RNA interference. Reduction in the synthesis of NSP5, as shown by immunoblot and immunofluorescence assays, correlated with a reduction in the number and size of viroplasms and with an altered intracellular distribution of other viroplasm-associated proteins. Silencing of gene 11 also resulted in a reduced synthesis of viral RNA(+) and double-stranded RNA and of all viral proteins, as well as in a decreased production of infectious virus. A similar phenotype was observed when the NSP5 coding gene of the lapine rotavirus strain Alabama was silenced. The fact that the NSP5 gene of rotavirus Alabama lacks the AUG initiator codon for a complete NSP6 protein, suggests that the described phenotype in gene 11-silenced cells is mostly due to the absence of NSP5. The data presented in this work suggest that NSP5 is a key protein during the replication cycle of rotaviruses.

Animals↗
PubMed1999

Effects of channel cytoplasmic regions on the activation mechanisms of cardiac versus skeletal muscle Na(+) channels.

Functional comparison of skeletal muscle (rSkM1) and cardiac (hH1) voltage-gated sodium channel isoforms expressed in Chinese hamster ovary cells showed rSkM1 half-activation (V(a)) and inactivation (V(i)) voltages 7 and 10 mV more depolarized than hH1 V(a) and V(i), respectively. Internal papain perfusion removed fast inactivation from each isoform and caused a 20-mV hyperpolarizing shift in hH1 V(a), with an insignificant change in rSkM1 V(a). Activation voltage of the inactivation-deficient hH1 mutant, hH1Q3, was nearly identical to wild-type hH1 V(a), both before and after papain treatment, with hH1Q3 V(a) also shifted by nearly 20 mV after internal papain perfusion. These data indicate that while papain removes both hH1 and rSkM1 inactivation, it has a second effect only on hH1 that causes a shift in activation voltage. Internal treatment with an antibody directed against the III-IV linker essentially mimicked papain treatment by removing some inactivation from each isoform and causing a 12-mV shift in hH1 V(a), while rSkM1 V(a) remained constant. This suggests that some channel segment within, near, or interacting with the III-IV linker is involved in establishing hH1 activation voltage. Together the data show that rSkM1 and hH1 activation mechanisms are different and are the first to suggest a role for a cytoplasmic structure in the voltage-dependent activation of cardiac sodium channels.

Amino Acid Sequence↗
PubMed1981

Valve morphogenesis and the microtubule center of the diatom Hantzschia amphioxys.

The siliceous valve of Hantzschia is briefly described, preparatory to following its morphogenesis. While Hantzschia is morphologically very different to Pinnularia, there are several subtle but important similarities in detail. Bundles of microfilaments, significant in generating the gliding motion of these cells, line the cytoplasmic fissure of the raphe. Valve morphogenesis in Hantzschia has been followed in live cells and by using transmission electron microscopy. Major re-organization and translocation of individual organelles, and also the nascent wall and its associated system of structural cytoplasmic components, are described. The spindle always forms on the concave side of the cell, opposite the raphes in the keels. A "polar complex" near each spindle pole consolidates into the "microtubule center" (MC) after cytokinesis. Each MC moves around its daughter nucleus to the center of the completed cleavage furrow and comes to rest on the narrow silicalemma running along the center of the cell. Microfilaments line first one and then both sides of the silicalemma before it grows outwards and begins to secrete the wall. Microtubules (MTs) extend along the silicalemma from the MC and directly over the future raphe; a compact row of mitochondria is organized along these MTs, flanking each MC. After about one hour in this central position, the whole assemblage of MC, MTs, mitochondria and silicalemma with its forming wall, move laterally across to the convex side of the parent valves. Now, the valve thickens steadily. The fibulae that hold the wall together where it is perforated by the raphe, grow out as flanges fusing with the transverse ribs across the keel. As in Pinnularia, the raphe fissure is occluded precisely adjacent to the MC, which also suppresses formation of the fibulae in this restricted region. The nascent wall structure suggests that silica is being precipitated on to a fibrous base. After valve formation, each MC migrates back to its interphase position at the concave side of the daughter cell. The MC undergoes characteristic morphological changes during these morphogenetic events and remains throughout tightly associated with a pronounced evagination of the nucleus. Ultrastructural comparisons suggest that the Hantzschia symmetry could have originally been derived from that of Pinnularia.

Cell Membrane↗
PubMed1996

Long-term structural alterations to endothelial cells in vein-to-artery grafts: a quantitative electron microscopic study.

The intracellular structure of endothelium lining vein-to-artery grafts in rats was analysed, using transmission electron microscopy and morphometry, to determine the ultrastructural adaptations of endothelial cells in this altered vascular environment. Autogenous 4-mm sections of iliolumbar veins were inserted microsurgically into the left common iliac arteries of 16 male Wistar rats. At 3, 6, 26 and 52 weeks the cytoplasmic-vesicular, mitochondrial and rough endoplasmic reticular contents of endothelial cells lining the grafts, the opposite iliac arteries and the remaining ilio-lumbar veins were analysed morphometrically. There was a significant increase in the amount of all these cytoplasmic structures in endothelial cells at 3, 6 and 26 weeks, at 52 weeks there was also a significant increase in the volumes of mitochondria and cytoplasmic vesicles, but not in rough endoplasmic reticulum. It was concluded that the ultrastructure of endothelial cells lining these grafts is changed chronically after graft insertion, and we propose that this may be attributable to altered haemodynamic stresses within the graft.

Animals↗
PubMed1990

Ultrastructural study of lamellar and nucleolus-like bodies in the harderian gland during postnatal development of the hamster (Mesocricetus auratus).

Membranous structures identified as lamellar bodies (LBs) and dense intracytoplasmic bodies referred to as nucleolus-like bodies (NLBs) have been found in the hamster Harderian gland during neonatal stages. Both structures appear between 8 and 12 postnatal days, coinciding with the beginning of secretory activity. LBs in males and NLBs in both sexes gradually decrease in number with further differentiation of the glandular cells. The morphological features of these cytoplasmic structures are described, and their origin as well as their possible functional significance are discussed.

Animals↗
PubMed1983

Ultrastructural networks in growth cones and neurites of cultured central nervous system neurons.

We have examined growth cones and neurites of cultured central nervous system neurons by high-voltage electron microscopy. Embryonic chicken retina cells were cultured on polylysine-treated and Formvar-coated gold grids for 2-6 days, fixed, and critical point dried. Growth cones and neurites were examined as unembedded whole mounts. Three-dimensional images from stereo-pair electron micrographs of these regions showed a high degree of ultrastructural articulation, with distinct, non-tapering filaments (5-9 nm in diameter) joining both cytoskeletal and membranous components. In the central regions of growth cones, interconnected structures included microtubules, large membranous sacs (up to 400 nm), and irregular vesicles (25-75 nm). A denser filamentous network was prevalent at the edges of growth cones. This network, which frequently adjoined the surface membrane, linked vesicles of uniform size (35-40 nm). Such vesicles often were seen densely packed in growth cone protrusions that were about the size of small synaptic boutons. Prevalent structural interconnections within growth cones conceivably could play a logistic role in specific membrane assembly, intracellular transport, endocytosis, and secretion. Because such processes are not unique to growth cones, the extensive linkages we have observed may have implications for cytoplasmic structure in general.

Animals↗
PubMed1979

[Particular ultrastructural aspects of human Paneth's cells].

Our research is about the ultrastructural aspects of Paneth cells obtained from human jejunal mucosa. The cells appear columnar in shape and show a roundish nucleus; their cytoplasm is characterized by a great amount of R.E.R. and by typical large granules in sopranuclear position. Our results confirm those previously described by other authors about the morphology of Paneth cells. In our specimens we have found moreover a variable number of particular cytoplasmic structures; these may show a fibrillar or granular matrix and are always surrounded by a membrane.

Cell Nucleus↗
PubMed1982

Fine structure of human two-cell ova fertilized and cleaved in vitro.

The human two-cell ovum consists of two equally sized blastomeres, surrounded by the zona pellucida. Cumulus cells may be apposed to the exterior of the zona. The blastomere nuclei contain spherical nucleoli, made up of fibrillar matrix, and randomly dispersed chromatin. The cytoplasmic structures include mitochondria, smooth endoplasmic reticulum, annulate lamellas, the Golgi complex, free ribosomes, secondary lysosomes, cortical granules, and microtubules. The cell membrane bristles with microvilli and displays signs of pinocytosis except at the site of apposition of the two blastomeres. The fine structure of the two-cell ova fertilized and cleaved in vitro corresponds with the presumptive pattern with respect to the current knowledge of mammalian embryo preimplantation development. The ova seem to have been capable of further growth.

Adult↗
PubMed1977

Polarized bundles of actin filaments within microvilli of fertilized sea urchin eggs.

We report on the internal ultrastructure of long, finger-like microvilli which cover the surface of the fertilized sea urchin egg. Eggs were attached to polylysine-coated surfaces; their upper portions were sheared away with a stream of buffer which left behind only their plasma membranes and adjacent cytoplasmic structures. Scanning electron microscopy (EM) of such fragments revealed intact thin protoplasmic projections radiating away from the body of the cortex. By transmission EM of cortices similarly prepared on grids, small bundles of microfilaments appear as cores within the thin cytoplasmic projections. These microfilaments are shown to be composed of actin by their ability to interact with muscle heavy meromyosin (HMM). HMM-decorated microfilaments possess repeating arrowheads which uniformly point toward the cell interior. Actin bundles in the microvilli of sea urchin eggs may mediate microvillus support and elongation.

Actins↗
PubMed1998

Choriocapillary changes and hyperfluorescence on indocyanine green angiography.

BACKGROUND: The purpose of this study is to examine the relationship between pathological changes of the choriocapillaris (CC) and the finding of bright fluorescence on indocyanine green (ICG) angiography. METHODS: An animal model was used, with chorioretinal lesions produced by injecting sodium iodate 3 h, 24 h, 7 days or 14 days previously. The ICG angiographic findings were compared with histology. RESULTS: Three hours after injection, many spots of bright fluorescence were scattered at the posterior pole. Histologically, variable changes in CC endothelial cells were observed. In some regions, the cells remained almost normal morphologically. In other regions, the endothelial cytoplasm was thickened with decreased fenestrations, or precipitation of fibrin in the choroidal interstitium was observed. Twenty-four hours after injection, the area of bright fluorescence had extended beyond that observed after 3 h. Histologically, the cytoplasmic structure of CC endothelial cells was unclear, and the endothelial walls were detached from the basement membrane. When ferritin was administered as a tracer, many ferritin granules were observed in Bruch's membrane. Seven days after injection, the degree of bright fluorescence was reduced as compared with 3 and 24 h after injection. Histologically, the cytoplasm of CC endothelial cells was thinned, but contained few fenestrations. The endothelial walls were detached from the basement membrane. Fourteen days after injection, normal diffuse ICG fluorescence was observed. Histologically, CC endothelial cells exhibited almost normal structure. CONCLUSION: These findings indicate that changes in CC endothelial cells and bright fluorescence on ICG angiography are closely related. ICG angiography should enable clinical evaluation of increased permeability of CC endothelial cells to relatively large molecules.

Animals↗
PubMed1961

Maturation of the rat fetal thyroid.

Maturation of the rat fetal thyroid was studied with the aid of I(131) and of fluorescence and electron microscopy. The I(131) concentration of the fetal gland increased exponentially from day 17 to day 20 of gestation and was related to the weight of the fetus (and presumably the weight of the thyroid) and also to the quantity of I(131) accumulated by the fetus. In the 17-day gland, thyroglobulin or immunologically similar material was sparsely present in the incipient lumens of some cell clusters. With maturation, this material increased and was also observed within follicular cells on days 18 to 19 of gestation. On day 20, the specifically reacting material was present in the follicular lumens and was absent from the cytoplasm of follicular epithelium. Ultrastructurally, the earliest thyroid cells examined were replete with all the organelles found in the more mature epithelium. No direct correlation could be made between the cytoplasmic structures and the presence of thyroglobulin, although the granular endoplasmic reticulum was most likely the organelle responsible for synthesis of thyroglobulin. Thyroglobulin or a precursor was found in fetal thyroid cells before measurable quantities of I(131) were concentrated and before cytoplasmic droplets appeared.

Animals↗
PubMed1977

The pituitary of Aphanius dispar (Rüppell) from hypersaline marshes and freshwater. II. Ultrastructure of the rostral pars distalis.

An ultrastructural study of the rostral pars distalis of the pituitary of Aphanius dispar specimens taken from freshwater or hypersaline marshes revealed significant structural differences which indicate higher activity of the prolactin cells in the hypotonic medium. Prolactin cells from freshwater specimens had larger secretory granules, a higher amount of endoplasmic reticulum, and expanded intercellular spaces with many secretory lakes. These cells contained an unusual cytoplasmic structure, consisting of twisted canals with vesicular lumina, connected to the endoplasmic reticulum of the cell. This structure is about 1-2 micron in diameter. Stellate cells are characterized by extracellular spacing junctions which are particularly noticeable at the confluence of the interstellate cell canaliculi and the pericapillary space.

Animals↗
PubMed2004

Apoptosis in wheat seedlings grown under normal daylight.

Apoptosis was observed in the coleoptile and initial leaf in 5-8-day-old wheat seedlings grown under normal daylight. Apoptosis is an obligatory event in early wheat plant ontogenesis, and it is characterized by cytoplasmic structural reorganization and fragmentation, in particular, with the appearance in vacuoles of specific vesicles containing intact organelles, chromatin condensation and margination in the nucleus, and internucleosomal fragmentation of nuclear DNA. The earliest signs of programmed cell death (PCD) were observed in the cytoplasm, but the elements of apoptotic degradation in the nucleus appeared later. Nuclear DNA fragmentation was detected after chromatin condensation and the appearance in vacuoles of specific vesicles containing mitochondria. Two PCD varieties were observed in the initial leaf of 5-day-old seedlings grown under normal daylight: a proper apoptosis and vacuolar collapse. On the contrary, PCD in coleoptiles under various growing (light) conditions and in the initial leaf of etiolated seedlings is only a classical plant apoptosis. Therefore, various tissue-specific and light-dependent PCD forms do exist in plants. Amounts of O2*- and H2O2 evolved by seedlings grown under normal daylight are less than that evolved by etiolated seedlings. The amount of H2O2 formed in the presence of sodium salicylate or azide by seedlings grown under normal daylight was increased. Contrary to etiolated seedlings, the antioxidant BHT (ionol) did not inhibit O2*- formation and apoptosis and it had no influence on ontogenesis in the seedlings grown under normal daylight. Thus, in plants grown under the normal light regime the powerful system controlling the balance between formation and inactivation of reactive oxygen species (ROS) does exist and it effectively functions. This system is responsible for maintenance of cell homeostasis, and it regulates the crucial ROS level controlling plant growth and development. In etiolated plants, this system seems to be absent, or it is much less effective.

Antioxidants↗
PubMed1990

Characterization by monoclonal antibody of a highly conserved antigenic determinant expressed on human platelet membranes and intermediate filament type III.

The murine monoclonal antibody (MoAb) CB21, raised after immunization with sonicated extracts of human platelets, has been shown to react with a line-restricted surface molecule and also a cytoplasmic structure displaying no restriction in terms of lineage and species. The surface structure recognized by the CB21 MoAb is exclusively expressed on the surface membrane of human platelets, being undetectable on other cells or lines so far tested. After permeabilization, the majority of the cells and lines tested with the CB21 MoAb displayed strong cytoplasmic reactivity with a constant typical filamentous distribution. Biochemical and morphological analyses showed that the cytoplasmic counterpart recognized by the CB21 MoAb is the intermediate filament type III.

Animals↗
PubMedDate not supplied

Plaque assay and replication of Tipula iridescent virus in Spodoptera frugiperda ovarian cells.

A plaque assay was developed for the study of Tipula iridescent virus (TIV) replication using a cell line derived from the fall army worm Spodoptera frugiperda (Sf9). Infection and plaque formation were monitored with time by phase contrast microscopy, video and fluorescent light microscopy. Structure of virions, viroplasmic centres and organelles of infected cells were examined by transmission electron microscopy (TEM). After 4 h postinfection, plaques were visibly detected within the cell monolayer by the presence of localized cell damage and production of numerous vesicular-like cytoplasmic structures. Quantitation of virions present per A260 unit of TIV preparation was determined by TEM. The number of visible plaques corresponded to virus concentration and 1 A260 produced approximately 10(5) plaques. DNA hybridization analysis revealed no gross differences in genomic DNA from TIV propagated in either Sf9 cells or wax moth Galleria mellonella larvae. These findings indicate that Sf9 is permissive for replication of TIV and superior by some parameters to other cell lines currently in use for the study of host cell/TIV interactions.

Animals↗