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F Miragall

Publications and source records attributed to F Miragall.

35 records · Page 2Linked to original sources
PubMed1986

Morphological differentiation of mitochondria in the early chick embryo: a stereological analysis.

The morphological evolution of mitochondria in three cell types of chick embryo in neurulation was analyzed by stereological methods. Mitochondria, showing a random distribution, were characterized by moderate electron-dense matrices and normal cristae. The numerical density of mitochondria significantly increased in the neuroectoderm and epiblastic cells while their volume density remained unchanged. The mitochondria in mesoderm cells were ellipsoidal (axial ratio 2:1) at stages 5 and 8 although they underwent an elongation in neuroectoderm and epiblastic cells (axial ratio from 2:1 to 1.6:1). The individual size of "average mitochondria" in the mesoderm cells was smaller than in other cell types. The total V/S (volume/surface) ratio of mitochondria decreased during neurulation. These morphological changes have been discussed emphasizing the possible metabolical role of mitochondria during morphogenesis.

Animals↗
PubMed1986

Orthogonal arrays of particles in the plasma membrane of pneumocytes.

The presence of orthogonal arrays of particles (OAP) in pneumocytic membranes was studied using freeze-fracture replicas of lung tissue from turtles, frogs and various mammalian species, including man. OAP are typically present in the basal plasma membrane of pneumocytes in turtles and frogs, while they have only been detected in the plasma membrane of type I cells in human lungs among the mammalian species studied. The median of particles per OAP was 10 (range 4-40) in lower vertebrates and 8 (range 4-24) in man. The mean density of OAP per unit cell surface varied between 40 and 60/micron2. The frequent occurrence of OAP in pneumocytic membranes in the lungs of man, turtles, and frogs suggests that they are related to a specific, although undetermined pulmonary function which is restricted to the ciliated airway epithelium in those mammalian species lacking OAP in the alveolar epithelium.

Animals↗
PubMed1985

Endocytosis of cationized ferritin in human peripheral blood by resting T-lymphocytes.

We have examined the binding and internalization of cationized ferritin in T-lymphocytes of human peripheral blood, as a model for resting cells. After 30 min of incubation only 8% of endocytotic vesicles contain cationized ferritin. T-cells internalize the equivalent of their entire surface area in approximately 54 h, a longer time than is required by non-resting cells such as PHA-stimulated human lymphocytes. These tracer experiments suggest that the endocytosis of cationized ferritin by T-lymphocytes follows a lysosome pathway similar to that described for other cell types.

Biological Transport, Active↗
PubMed1985

Distribution of concanavalin-A receptor sites on the surface of human resting T lymphocytes. A stereological study using concanavalin-A/colloidal-gold-labelled horseradish peroxidase.

Stereologic techniques were used to analyse the density and distribution of Concanavalin-A (Con-A) receptor sites on the surface of isolated resting human peripheral-blood T lymphocytes using Con-A/colloidal-gold-labelled horseradish peroxidase. The T-lymphocyte surface appeared to be composed of microvilli, smooth areas and uncoated pits. Coated pits and coated vesicles, identified by the preferential staining of clathrin-containing membranes (tannic-acid/saponin fixation), were scarce. Quantitative analysis of the gold labelling on T lymphocytes after glutaraldehyde fixation indicated the presence of 2.13 +/- 0.46 gold particles per micron of cell surface and that these particles were preferentially located on uncoated pits. These results suggest the existence of cell-surface domains for these receptor sites in human resting T lymphocytes.

Coated Pits, Cell-Membrane↗
PubMed1985

Alterations in the cytochemical activity of several phosphatases in hepatocytes from rats exposed prenatally to ethanol.

The activities of acid phosphatase, alkaline phosphatase, glucose-6-phosphatase, uridine diphosphatase, inosine diphosphatase, thiamine pyrophosphatase and 5'-nucleotidase have been investigated cytochemically in hepatocytes of the offspring of alcohol-fed rats, using cerium ions as a capturing agent and qualitative and quantitative electron microscopy. All these enzyme activities were decreased in the experimental animals compared with controls not exposed to ethanol. The pattern of deposition of the product of glucose-6-phosphatase activity in the cisternae of the endoplasmic reticulum was also different in the two groups. The phosphatases analyzed are functional markers of different cell components, and the results suggest that prenatal exposure of rats to ethanol causes functional alterations in the endoplasmic reticulum, Golgi apparatus, lysosomes and plasma membrane of hepatocytes.

Animals↗
PubMed1984

Freeze-fracture study of the plasma membranes of the septal olfactory organ of Masera.

The olfactory border and the apical cell contacts of the organ of Masera (MO) of the mouse were investigated by freeze-fracture electron microscopy. The olfactory border is mainly composed of the terminals of receptor and supporting cells. Cells with thick microvillus-like projections, though less frequent than the other two cell types, also contribute to the border. Olfactory knobs show transitions between those displaying numerous cilia and those characterized by few or no cilia. The olfactory cilia have a typical necklace of 6-9 rows of particles. The eruption of developing cilia seems to be preceded by the formation of circular arrays of particles. The density of intramembranous particles (IMP) per micron2 in P- and E-faces of the ciliary membranes is 1095 +/- 190 and 205 +/- 65, respectively. In the microvilli of supporting cells, the density of IMP per micron2 is 1800 +/- 270 for the P-face and 570 +/- 135 for the E-face. At the base of the supporting cell microvilli, rod-shaped particles are observed. The lateral plasma membranes of these cells bear orthogonal arrays of particles. In the apical region of the MO neuroepithelium, extensive zonulae occludentes are present which seal the intercellular cleft. The zonulae occludentes between supporting and receptor cells are composed of 5-13 junctional strands, usually arranged in an elongate network. Zonulae occludentes between supporting cells are, in addition to the elongate network, also arranged in a mesh-like pattern. Gap junctions, both associated with the zonulae occludentes and independent of them, are occasionally found between supporting cells. The results obtained indicate that important similarities exist between the neuroepithelium of the MO and the olfactory epithelium proper, whereas remarkable differences exist between the MO and the vomeronasal neuroepithelium.

Animals↗
PubMed1984

Ultrastructural analysis of human plasmacytoma cells prepared on affinity beads after exposure to anti-idiotype antibodies.

Mononuclear cells from a bone marrow infiltrated by plasmacytoma cells were examined by electron microscopy. An analysis was performed according to different cytoarchitectural forms of the endoplasmic reticulum (ER). Six types of plasma cells could be distinguished. The bone marrow cells were treated with an anti-idiotype antiserum from a guinea pig prepared against the patient's monoclonal serum protein and with a FITC conjugated anti-guinea pig antiserum from the rabbit as second layer. Then the cells were passed through an affinity gel column with anti-FITC antibodies. The original preparation and the cells separated on the affinity gel were analysed by electron microscopy. It was found that an ultrastructurally distinct type of plasma cell was enriched 3.5-fold over the original sample by the separation procedure.

Antibodies, Anti-Idiotypic↗
PubMed1983

Evidence for orthogonal arrays of particles in the plasma membranes of olfactory and vomeronasal sensory neurons of vertebrates.

Plasma membranes of sensory neurons from the olfactory and vomeronasal neuroepithelia of the male rat and olfactory neuroepithelium of the tiger salamander (Ambystoma tigrinum) have been examined, using the freeze-fracture technique, for the presence and morphology of orthogonal arrays of particles (OAP). Numerous OAP were scattered on the P-face of plasma membranes of the dendrites and cell bodies from rat vomeronasal sensory neurons. The OAP were 720 +/- 200 nm2 in area and they consisted of 4 to 20 particles whose centre-to-centre distance was about 7 nm. On the E-face, complementary orthogonal arrays of pits were observed. No OAP were detected in the olfactory sensory neurons of the rat. In the dendritic and perikaryal plasma membranes of the tiger salamander olfactory sensory neurons, OAP 2230 +/- 970 nm2 in area were observed on the P-face. The OAP consisted of 12 to 36 particles. The centre-to-centre distance of the particles was about 7 nm. In the olfactory receptor cell plasma membranes of this species, OAP formed complexes of 2 to 28 individual OAP, the longitudinal axes of which were usually arranged in parallel. Complementary complexes of orthogonal arrays of pits were observed on the E-face.

Ambystoma↗
PubMed1982

Experimental studies on the olfactory marker protein. II. Appearance of the olfactory marker protein during differentiation of the olfactory sensory neurons of mouse: an immunohistochemical and autoradiographic study.

The time interval between the incorporation of [3H]thymidine and the appearance of olfactory marker protein (OMP) in autoradiographically labeled neurons which have differentiated from stem cells, has been determined by autoradiographic and immunohistochemical techniques. The first [3H]thymidine-labeled, OMP-containing elements have been observed 7 days after administration of the radioactive thymidine. This result allows some speculation on the potential function of the olfactory marker protein.

Animals↗
PubMed1982

Extramedullary multiple myeloma. A qualitative and quantitative electron microscopic study.

A case of multiple myeloma with a mediastinal tumor and other unusual findings is described. The findings included the presence of extramedullary tumor masses at multiple sites in addition to the medullary tumor and, more interestingly, the occurrence of pleural and peritoneal effusions. The plasma cells from these effusions were analyzed using stereological morphometric methods. The plasma cells were also cultured and established as a continuous cell line and were studied using the same methods. Our results indicate that there are qualitative and quantitative morphologic differences between the pleural and peritoneal plasma cells. Comparison between plasma cells and cultured cells from the intraperitoneal exudate showed marked morphologic differences. The analysis of these differences indicated that mature plasma cells, when subjected to culture, were transformed into immature lymphoid cells.

Aged↗
PubMed1982

Cell migration from the chick olfactory placode: a light and electron microscopic study.

The differentiation of the olfactory placode in the chick has been studied using light and electron microscopy. Special attention was paid to the appearance of neuronal cells within the placodal ectodermal thickening, the migration of cells out of this tissue and the appearance of the first fila olfactoria in the differentiating olfactory mucosa. Between the third and fifth day of incubation a large number of cells is observed leaving the base of the invaginating olfactory placode, often in contact with thin axon bundles. These cells are characterized by a well-developed Golgi apparatus, a considerable number of mitochondria and dense-core vesicles. The morphology of these migrating cells resembles that of cells observed near the basement membrane within the developing olfactory epithelium and is clearly different from the mesenchymal cells which are filled with polyribosomes. At the sixth day of incubation thick axon bundles can be observed within the epithelium and the underlying lamina propria. The possible fate of the migrated epitheloid cells is discussed.

Animals↗
PubMed1982

Intercellular junctions in the rat vomeronasal neuroepithelium: a freeze-fracture study.

The intercellular junctions (tight junctions, desmosomes and gasp junctions) of the vomeronasal neuroepithelium of male Wistar rats were investigated by freeze-fracture. Tight junctions were localized apically sealing the intercellular clefts. Tight junctions were composed of 6 to 12 junctional strands arranged in a meshwork. the distance between the most apical and the most basal junctional strand was 430 +/- 90 nm. No proper distinction could be made between receptor-supporting and supporting-supporting cell tight junctions. Besides tight junctions, numerous desmosomes and ga junctions were found. Desmosomes were present on the supporting and receptor cell membranes below the level of the tight junctions. Gap junctions could be seen at the level of the perikarya of the supporting and receptor cells. They were only found on supporting cell membranes.

Animals↗
PubMed1980

Freeze-etching studies on the ciliary necklace in the rat and chick.

The existence of a ciliary necklace in kinocilia, atypical cilia and mature and differentiating sensory cilia is described in rat and chicken. In addition to parallel horizontally oriented rows of the ciliary necklace, irregular forms of intramembranous particle (IMP) aggregations are also described. The function of the ciliary necklace is discussed, special attention being given to the appearance of circular rows of IMP prior to the outgrowth of olfactory cilia and to the existence of dynein arms in these. Evidence is provided for the motility of olfactory cilia in the chick.

Animals↗
PubMed1979

Ultrastructural investigation on the cell membranes of the vomeronasal organ in the rat: a freeze-etching study.

The free surfaces and cell contacts in the epithelia of the vomeronasal organ of the rat were investigated by freeze-etching. The microvilli of receptor cells show a lower density of intramembranous particles (IMP) than the microvilli in the receptor-free epithelium. The ratio between the IMP on P- and E-face is approximately 11 : 1 in the receptor terminals, and 3.5 : 1 in the cilia and microvilli of the receptor-free epithelium. Although atypical in length and only poorly equipped with rootlet fibers, the cilia of the receptor-free epithelium are furnished with typical ciliary necklace structures of up to 10 rows of membrane particles. Differences in the density of IMP on the P-faces of different cilia are probably due to continual ciliogenesis and also due to the different age of cilia in the receptor-free epithelium. Zonulae occludentes show different configurations in the neuroepithelium and in the receptor-free epithelium. In the former, they show a tendency to cross-link and form facet-like patterns, reflecting a constant morphology and relative stability for this apical region. In the receptor-free epithelium the junctional rows of zonulae occludentes display only loosely interconnected networks and a tendency to orient parallel to each other and to the free surface. In addition to zonulae occludentes, typical square aggregations of IMP are observed in the receptor-free epithelium. They are not exclusively restricted to the zone of intensive cell contacts by means of fine interdigitating cell processes, and their function has yet to be identified experimentally.

Animals↗
PubMed1979

Electron microscopic morphometric analysis of small cortical and medullary thymocytes from the rat.

Electron microscopic morphometric analysis of rat small thymocytes reveals quantitative differences between small cortical and medullary thymocytes. The unit gravity velocity sedimentation technique was used to obtain a cellular pool composed mainly of small sized thymocytes. Stimulation "in vitro" with phytohemagglutinin followed by cell size separation was employed to separate cortical small thymocytes. Furthermore, isolation of medullary small thymocytes was carried out by treatment "in vivo" with hydrocortisone. Our results show that the majority of the quantitative changes correspond to differences in the distribution of chromatin and the density of perichromatin granules. They demonstrate the importance of chromatin pattern analysis for the identification of small cortical and medullary thymocytes.

Animals↗
PubMed1978

Surface features of small thymocytes of rat: a freeze-fracture and scanning electron microscope study.

The surface of small thymocytes of 6 day old rats has been examined by freeze-fracture and scanning electron microscopy. Various procedures were used to enrich the cell population and protect their surfaces. On the basis of morphological criteria, three types of small thymocytes: smooth thymocytes (79.5% of total cells), thymocytes characterized by the presence of ridge-like profiles (16.1%) and thymocytes displaying a moderate number of small microvilli (2.4%). From the results after stimulation with PHA and later separation, it is concluded that the first population corresponds to small cortical thymocytes, and the second to small medullary thymocytes.

Animals↗