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D Septier

Publications and source records attributed to D Septier.

At least 73 records · Page 4Linked to original sources
PubMed1988

Lipid detection by malachite green-aldehyde in the dental basement membrane in the rat incisor.

Developing rat incisors were treated with malachite green-aldehyde fixative solution (MGA), which retains and stains lipids. We observed positive staining occurring as dots in the basement membrane. Most of these dots (2-3.5 nm in diameter) were grouped in the lamina densa but some were also present in the lamina lucida and the lamina fibroreticularis. These data provide evidence for the existence of lipids in the dental basement membrane and suggest that they are distributed together with the various groups of proteins so far detected.

Aldehydes↗
PubMed1987

Visualization of proteoglycans and membrane-associated components in rat incisor enamel organ using ruthenium hexammine trichloride.

Ruthenium hexammine trichloride (RHT) revealed granules of proteoglycans in the ground substance of the intercellular spaces of the outer enamel epithelium and stellate reticulum. Strong RHT-positive staining underlined the plasma membrane and filled the narrow intercellular spaces in a zone confined to the stratum intermedium and the basal part of the secretory ameloblasts. In the presecretory ameloblasts, this staining was either faint or absent. Its pattern suggests that proteoglycans and/or other groups of polyanions are functionally implicated in the transport and diffusion that allow delivery of metabolites near the basal part of the secretory ameloblasts.

Animals↗
PubMed1986

Ultrastructural location of complex carbohydrates in developing rat incisor enamel.

The ultrastructural distribution of complex carbohydrates in an early formation stage of rat incisor enamel was investigated by staining with the periodic acid-thiocarbohydrazide-silver proteinate reaction (PA-TCH-SP) for vicinal glycol-containing glycoconjugates, the phosphotungstic acid-chromic acid mixture (PTA) for glycoproteins, and the cationic dyes alcian blue or bismuth nitrate for sulfated glycoconjugates. In order to remove selectively sulfated complex carbohydrates, half of the serial sections obtained were digested with a bovine testicular hyaluronidase prior to staining. Far fewer electron-dense deposits were observed with the PA-TCH-SP method on hyaluronidase-treated sections, especially those subsequently treated for 48 hours with TCH. On the other hand, the minimal staining obtained with PTA was much more intense on sections treated with hyaluronidase where linear fiberlike structures were observed. With cationic dyes, staining of dotlike alignment structures and ground substance was obtained but was completely abolished by hyaluronidase treatment. Cuprolinic blue in a critical electrolyte concentration, ruthenium hexamine trichloride used with aldehyde during fixation, as well as rapid-freezing followed by freeze-substitution validate that this dotlike distribution is not an artefact of processing. The staining results demonstrated that the glycoproteins and sulfated complex carbohydrates in developing rat incisor enamel each display a specific distribution pattern. The glycoproteins were present as fiberlike structures and the sulfated carbohydrates appeared as dotlike formations located close to the surface of the fiberlike structures, and/or in the spaces between them.

Animals↗
PubMed1986

Visualization of proteoglycans and membrane-associated components in rat incisor predentine and dentine using ruthenium hexammine trichloride.

Ruthenium hexammine trichloride (RHT) used as a probe to visualize anion groups in the predentine and dentine of rat incisors, showed a complex distribution pattern including: intercellular proteoglycans (Pg), detected in the predentine as granules 10-15 nm in diameter and as filaments. Non-aggregating Pg was observed in the spaces between collagen fibres as an amorphous group substance. The dentine included smaller RHT-positive granules, observed after thin-section demineralization; pericellular aggregates, 30-50 nm in diameter, which were absent at the onset of the cell coat along the plasma-membrane of the odontoblast process and of the membrane itself. All these RHT-positive components might be Pg and/or sialoglyconjugates and glyco- or phospholipids present on the plasma membrane.

Animals↗
PubMed1985

Improved lipid preservation by malachite green-glutaraldehyde fixation in rat incisor predentine and dentine.

A network of granules and filaments stained with malachite green-aldehyde (MGA) was observed in predentine in the spaces between the collagen fibres and many small granules were associated with these fibres in peripheral and circumpulpal-dentine. The granules were present throughout the entire thickness of the dentine, especially at the periphery of the calcospherites, although scarce or absent at their centre. This MGA-stainable material (i) resisted demineralization in acetic acid and EDTA solutions, and (ii) differed from non-collagenous material and crystal ghosts which stained on control sections after prior demineralization. In predentine, transport and diffusion of MGA-stainable material occurred in the direction of the dentine in which this material was associated with periodical striation of mineralized collagen fibres. This suggests that true matrix-associated lipids might play a role in dentine mineralization.

Aldehydes↗
PubMed1984

Effect of dissociative extraction with 1.5 M calcium chloride on proteoglycans in rat-incisor predentine visualized with cuprolinic blue.

Treatment of rat-incisor predentine for 48 h in a 1.5 M CaCl2 solution halved the number and size of the proteoglycan precipitates visualized using a critical MgCl2 concentration and cuprolinic blue staining. About 75 per cent of the aggregable proteoglycans were extracted; 25 per cent resisted extraction. Treatment with CaCl2 also completely abolished the electron density of the amorphous ground substance, an observation consistent with the possible existence of two classes of proteoglycans in predentine.

Animals↗
PubMed1984

[Demonstration of lipids by imidazole-buffered osmium tetroxide in the odontoblasts and cells of the enamel organ in the rat incisor].

Tissue post-fixation with imidazole buffered osmium tetroxide allows localization of lipids rich in unsaturated fatty acids (Angermüller and Fahimi, 1982). In odontoblasts, a positive reaction is observed in mitochondria, in membranous structures and in vesicles containing an osmiophilic and amorphous material. In odontoblastic processes, tubulo-vesicular structures and electron-dense coated vesicles seemed to be engaged in endocytosis and transfer processes towards lysosomial structures of the cell body. In the enamel organ, lipidic structures are observed in the stellate reticulum and the stratum intermedium. The plasma membrane of secretory ameloblasts as well as the content of some lysosomial structures are well contrasted. However the distal membranes of the Tomes processes showed weakly stained portions alternating with electron dense segments. Extracellular lipidic globules, sometimes associated with plasma membranes were also seen. These observations demonstrated the alternating weak and strong staining reactions in unsaturated fatty acids of plasma membrane areas of the cell processes, which contrasts with the continuous staining of the plasma membrane of the cell bodies. These observations could be related to functional differences.

Animals↗
PubMed1983

Electron microscopic visualization of proteoglycans in rat incisor predentine and dentine with cuprolinic blue.

Cuprolinic blue in a MgCl2-critical electrolyte concentration solution allows a larger surface representation of proteoglycans than other methods. Glycoaminoglycans in predentine were ribbon-like structures 14 nm thick and 60 nm long, with radiating filaments (3-4 nm) located in spaces between collagen fibres. Glycoaminoglycans and collagen together displayed longitudinal and orthogonal relationships. The ground substance was slightly electron dense. In dentine, the precipitate was less in quantity and consisted of rounded granules (15 nm in diameter, and filaments/3 nm in width) closely associated with the surfaces of collagen fibres.

Animals↗
PubMed1982

The effects of vinblastine on the cell structure and activity in the rat incisor enamel organ during the secretory stage in vivo as shown by radioautography using 3H-proline, 3H-serine and 3H-fucose.

Four hours after injection of vinblastine sulphate (VBL) the cells of the enamel organ of the rat incisor showed: 1) loss of polarity in the tall secretory ameloblasts--secretory granules, which were lacking in the Tomes processes accumulated in the supranuclear area; condensing vacuoles also accumulated near dictyosomes; enlarged intercellular spaces without disruption of intercellular junctions; lysosomal structures and autophagic vacuoles. 2) an increase of lysosome-like structures in the outer enamel epithelium, the stellate reticulum and the stratum intermedium. 3) a severe reduction in number of free ribosomes in the stratum intermedium as well as an increase in size of the Golgi complex: numerous electron lucent vesicles appeared. These findings as well as radioautographic data demonstrated 1) the impairment of secretory activity of ameloblasts. 2) the restriction of permeability in the enamel organ suggesting strong interaction between VBL and the membranes.

Ameloblasts↗
PubMed1982

[Use of dysprosium considered as an activable tracer in the study of tooth structures].

After 32 days of administration to rats of dysprosium in drinking water, this element has been studied by neutron activation analysis in the intra-oral part of the incisors as well as in the molar crowns. This element was absent in the intra-osseous parts of the incisors, the femurs and the liver. After intravenous injection of 13 mg or 26 mg of Dy in several doses over 32 days, this element was found in the incisor formation and maturation zones as well as in the part having erupted in the oral cavity. It was also found in the molars, the femurs and the liver. The structural study has shown that no cytotoxic effect was observed with the dysprosium doses used. Dentinogenesis and amelogenesis were not disturbed. The final structures were homogeneous. By comparing the two administration ways of dysprosium we have at our disposal a study model using an inducible tracer of the incorporation of adsorption of a mineral element in dental structures during early or late maturations.

Animals↗
PubMed1982

[Histochemical and morphometric study of the changes induced by the absorption of sodium fluoride on the submaxillary and sublingual glands in the rat].

Three groups of Osborn Mendel rats received for two weeks either drinking water without addition of fluorides (control rats) or drinking water containing respectively 50 and 100 ppm of sodium fluoride. The histochemical study of the submaxillary and sublingual glands showed a very strong decrease in the polysaccharide and protein stainings in the 100 ppm group, whereas the 50 ppm group showed similar reactions to the control group. The morphometric study showed a strong decrease of the acinar and canalicular surfaces mainly in the submandibular gland. Thus the absorption of high doses of sodium fluoride induced in these two salivary glands morphological changes of the secretory cellular units. An indirect way of action can thus be exerted in the oral cavity.

Animals↗
PubMed1981

[Freeze fracturing and thin-section study of intercellular junctions between odontoblasts and the rat incisor. Changes induced by vinblastine].

The study of thin sections and replicas obtained after freeze-fracture showed that the intercellular junctions of the young secretory odontoblasts of the rat incisor were of two types. Zonula adherens (desmosomes) united the cellular bodies at the predentinal border. Ahead of these structures gap junctions were observed. An injection of vinblastine sulfate induced 4h, a) an enlargement of intermembranous spaces between the gap junctions, b) a reduction of the contact surfaces in the desmosomes and c) a thickening of the intracytoplasmic dense material made of microfilaments, associated with the junctional complex. These modifications favoured the observation of these structures after freeze-fracture. The desmosome junctions could play a mechanical function (partitioning of the predentinal compartment) whereas the gap junction allowed the electrotonic coupling of the odontoblasts. They allowed however an intercellular diffusion route for ionic components (calcium) and matrix components of serum origin.

Animals↗