Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ODONTOBLASTS”

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 667 records · Page 37Linked to original sources
PubMed1984

Comparative radioautographic study of the effects of L-azetidine-2-carboxylic acid on matrix secretion and Golgi of the mouse incisor.

The effect of a proline analog, L-azetidine-2-carboxylic acid (LACA), on protein matrix secretion by odontoblasts and ameloblasts was compared by light and electron microscopic radioautography after injection of 3H-glycine in young mice. LACA inhibited the secretion of dentin matrix with consequent accumulation of 3H-glycine labeled procollagen in the cisternae of the rough endoplasmic reticulum. In contrast, LACA had no apparent effect on ameloblasts as enamel matrix continued to be packaged in the Golgi apparatus and secreted from Tomes' process within 30 min after injection of the radioprecursor. Electron microscopy revealed that LACA did not cause any change in ameloblast ultrastructure but produced a marked alteration of the odontoblast Golgi complex. All odontoblast Golgi saccules and collagen secretion granules disappeared within 2 h after LACA administration. Odontoblast Golgi cisternae, however, appeared not to be affected. These observations confirm previous studies conducted in this laboratory showing that Golgi saccules in collagen-secreting cells are the initial staging areas for the formation of secretory granules. These results also indicate that a close correlation exists between form and function in the Golgi apparatus of collagen-secreting cells.

Ameloblasts↗
PubMed2004

Nucleobindin--a Ca2+-binding protein present in the cells and mineralized tissues of the tooth.

Nucleobindin, a Ca2+-binding protein, has been previously identified within the nucleus and endoplasmic reticulum, and in association with the Golgi membrane. In addition, nucleobindin has been shown to be a minor constituent of bone extracellular matrix and has been postulated to play a role in mineralization. In the current investigation, we report the expression and localization of nucleobindin within odontoblasts and the dentin matrix. Nucleobindin mRNA transcripts were detected in the tooth, and in situ hybridization analysis substantiated the findings, showing nucleobindin expression within mature odontoblasts and within the cells of surrounding developing alveolar bone. Western blot analysis of tooth protein extracts demonstrated the presence of a 63 kDa protein, which showed immunologic affinity for a rat nucleobindin peptide antibody. The distribution of the protein was shown in mature odontoblasts by using immunohistochemistry. Moreover, immunogold labeling of nucleobindin and subsequent ultrastructural analysis demonstrated a similar pattern of distribution. Nucleobindin was identified within odontoblast cellular compartments: the nucleus, endoplasmic reticulum, and mitochondria. Of interest, nucleobindin localization was observed within the surrounding dentin extracellular matrix, and immunogold labeling was shown to accumulate with tissue development toward the cusp. The study clearly demonstrated the presence of nucleobindin within dental tissues. In consideration of the known functional properties of nucleobindin, it may be postulated that nucleobindin may contribute to the accumulation and transport of Ca2+ ions to the mineralization front prior to hydroxyapatite deposition.

Animals↗
PubMed1999

[3H]choline uptake and turnover into membrane and extracellular matrix phospholipids, visualized by radioautography in rat incisor dentin and enamel.

In order to study the uptake and fate of [3H]choline into cellular and extracellular phospholipids in the forming part of mandibular rat incisors, radioautography was carried out after treatment with the iodoplatinate reaction which retains phospholipids. Thirty minutes and 1 hour after the intravenous injection of the radiolabeled precursor, grain density in secretory odontoblasts and ameloblasts was not significantly above background labeling whereas dentin was actually labeled. Therefore, at this early period, odontoblasts cannot be responsible for the secretion of phospholipids incorporated into dentin, and intercellular diffusion of components originating from blood could explain this early dentin labeling. After 2 hours, odontoblasts and ameloblasts were labeled. In cells, grain density reached a maximum at 4 hours, reduced at 24 hours, and strongly decreased at 4 days. In predentin and enamel, grain density peaked at 24 hours and diminished at 4 days. However, in the forming enamel 4 days after the injection, labeling was twice as high as in any other compartment. Altogether, the results highlighted two distinct pathways for phospholipids in dental mineralized dental tissues: a first one shows evidence of early incorporation of [3H]choline into dentin resulting from intercellular diffusion independently from odontoblasts secretion, whereas inside the forming enamel, higher labeling and longer retention of choline-containing membrane components were detected between 4 hours and 4 days. This suggests an accumulation of membranes that are not subjected to rapid turnover in contrast with other dental compartments.

Ameloblasts↗
PubMed2006

Expression of HMGB1 during tooth development.

High mobility group box 1 (HMGB1) is a nuclear and cytosolic protein that can act as a transcription factor, a growth factor, or a cytokine. To elucidate a possible role for HMGB1 in tooth development, we have studied the expression of HMGB1 and its receptor RAGE (receptor for advanced glycation end-products) during the late fetal and early postnatal period of rat by using light- and electron-microscopic immunohistochemistry. Low HMGB1 protein expression was observed during fetal and newborn stages of tooth development. However, from postnatal day 5 (P5) onward, a marked increase occurred in the levels of the protein in most dental cell types. Expression was particularly high in ameloblasts and odontoblasts at regions of ongoing mineralization. Although most HMGB1 immunoreactivity was confined to cell nuclei, it was also present in odontoblast cytoplasm. At P5, ameloblasts and odontoblasts also showed RAGE immunoreactivity, and reverse transcription-polymerase chain reaction demonstrated both HMGB1 and RAGE mRNA in human dental pulp cells in vitro. Immunoblots performed on extracts from bovine dentin demonstrated a principal band at approximately 27 kDa, indicating that HMGB1 participates in tooth mineralization. The expression of both ligand and receptor suggests an autocrine/paracrine HMGB1 signalling axis in odontoblasts.

Adult↗
PubMed1984

Ultrastructure of the effects of calcitonin on the development of mouse tooth germs in vitro.

Mandibular first molars, from 17-day-old embryos, were cultivated in control medium or medium containing 0.1, 0.01 or 0.001 unit/ml of calcitonin (CT) for periods up to 10 days. In untreated tooth germs, cells of the dental papilla differentiated into pre-odontoblasts up to 4 days and predentine was seen on day 6. Cells treated with 0.1 unit/ml of CT differentiated into pre-odontoblasts up to 4 days, but no predentine was formed even after 10 days in culture. With 0.01 unit/ml, cells differentiated into odontoblasts, and had already secreted predentine a few days earlier than the untreated group. With 0.001 unit/ml, the developing germs were similar to the control explants during the entire 10-day cultivation period. The proportional area of rough endoplasmic reticulum to cytoplasm of the odontoblasts was low at 0.1 unit/ml of CT and high at 0.01 unit/ml compared to the untreated explants.

Animals↗
PubMed1989

Morphogenesis of mineralized tissues induced by neonatal mouse molar pulp isografts in the spleen.

Tooth pulps dissociated intact with EDTA were isografted for up to 40 days, and examined by light and electron microscopy for hard tissue morphodifferentiation. Grafts formed tubular dentine and osteodentine. Tubular dentine, penetrated regularly by elongated odontoblast processes, resembled normal dentine and was formed when the original odontoblasts continued normal matrix secretion. Osteodentine was formed by spindle-shaped cells with large round nuclei which presumably were transformed pulp cells, and incorporated the same elements as found in cells of non-tubular dentine. Occasionally, odontoblasts were contiguous with both the regular dentine and the osteodentine. Thus in EDTA-dissociated pulps transplanted to the spleen, the original odontoblasts produce tubular dentine and other pulp cell differentiate to form osteodentine.

Animals↗
PubMed1994

Dense innervation of human radicular dental pulp as revealed by immunocytochemistry for protein gene-product 9.5.

Protein gene-product 9.5 (PGP 9.5) is a novel neurone-specific protein. At light- and electron-microscopic levels, human radicular dental pulp was heavily innervated by PGP 9.5 nerve fibres. Thick nerve bundles showing intense PGP 9.5 immunoreactivity ascended in the centre of the pulp, with some nerve fibres extending from the trunk towards the peripheral pulp at regular intervals. However, the fibres did not form a plexus (of Raschkow) beneath the odontoblast cell layer. The PGP 9.5-positive nerve fibres penetrated into the predentine and dentine beyond the odontoblast cell layer where some nerves terminated. In the predentine, PGP 9.5-positive nerve fibres were densely distributed. In tangential sections along the pulpodentinal border, the nerve fibres ran in contact with odontoblast processes. Immunoelectron microscopy revealed that all nerve fibres were immunoreactive for PGP 9.5 in the radicular predentine and dentine, and terminated in contact with the odontoblast cell processes. The distribution pattern and terminal formation of predentinal and dentinal nerves were identical to those of coronal pulp, as reported previously. The dense innervation in radicular dental pulp, overlooked in previous reports, might be responsible for dentine hypersensitivity.

Adolescent↗
PubMed1990

Effects of beta-D-xyloside on morphogenesis and cytodifferentiation in cultured embryonic mouse molars.

Embryonic mouse molars were grown on a semi-solid medium supplemented with 2 mM beta-D-xylopyranoside (beta-xyloside), a specific inhibitor of proteoglycan synthesis. The induced glycosaminoglycan depletion in the extracellular matrix was monitored by immunohistochemistry employing monoclonal antibodies to chondroitin 4- and chondroitin 6-sulfates. beta-Xyloside inhibited formation of the dental bell and delayed the appearance of the first odontoblasts. Odontoblast functional differentiation proceeded in the absence of chondroitin sulfate in the basement membrane. Predentin secreted in the presence of beta-xyloside triggered the polarization of ameloblasts, but did not allow the maintenance of polarized odontoblasts. These results support the hypothesis that, in the tooth germ, chondroitin sulfate proteoglycans participate in the regulation of cell kinetic-dependent morphogenesis (Mark et al., 1990. Differentiation 43, 37-50). On the other hand, the possibility that chondroitin sulfate might play a role in odontoblast terminal differentiation is definitively ruled out.

Ameloblasts↗
PubMed2004

Role of injured endothelial cells in the recruitment of human pulp cells.

In restorative dentistry, deep cavity preparation may lead to partial destruction of the odontoblastic layer. However, newly formed odontoblast-like cells can replace the necrotic odontoblasts and secrete a reparative dentine matrix. While growth factors such as transforming growth factor beta1 (TGFbeta1) and bone morphogenetic proteins (BMP-2 and BMP-4) seem to be involved in the proliferation and differentiation of pulp cells, little is known about the migration of the newly proliferating stem cells to the injury site. Our hypothesis was that endothelial cell injury may be involved in directing these cells towards the injury site. For this study, human pulp fibroblasts and L929 cells were fluorescence-labeled by transduction with the Enhanced Green Fluorescent Protein (EGFP). Similarly, human umbilical vein endothelial cells (HUVEC) were labeled with the Discosoma Red Fluorescent Protein-2 (DsRed2). Cell migration was then studied in an insert cell culture system. The HUVEC cells were cultured in the lower compartment while the human pulp fibroblasts or L929 were in the upper compartment. After artificial injury to the HUVEC cells, only human pulp fibroblasts migrated to the lower compartment. At early time periods (4 days), migrating cells were randomly localized on the HUVEC layer. However, after 14 and 20 days, they were perfectly aligned along the injury site. In the absence of injury, no migration was observed. These results suggest that, the endothelial injury is involved in the recruitment of odontoblast-like cells at the injury site.

Cell Death↗
PubMed2002

Oxygen distribution and consumption in rat lower incisor pulp.

The aim was to determine the oxygen tension (P(O(2))) and rate of oxygen consumption in the pulp. Twelve rats were anaesthetised and artificially ventilated. Under an operating microscope, a recessed oxygen-sensitive microelectrode was inserted into the pulp through a small saline-covered cavity on the labial surface of the lower incisor. P(O(2)) was measured as a function of the transverse distance from the saline medium through to the middle of the pulp. Oxygen profiles were characterised by a decline of oxygen tension outside the pulp in the saline medium and a steeper gradient across the interface, before a localised oxygen consuming region corresponding to the odontoblasts. A plateau with some localised fluctuations was then followed by an increase in oxygen tension in the middle of the pulp. The average oxygen tension in the plateau region was 23.2 mmHg+/-2.1 mmHg (n=12). A mathematical model was used to extract oxygen consumption data from P(O(2)) profiles recorded from non-perfused pulp (created by reducing systemic blood pressure). The analysis revealed that there was a distinct oxygen consumption zone in the outer pulp, which anatomically corresponded to the odontoblast layer. The average oxygen consumption rate of the odontoblasts was 3.2+/-0.2 ml O(2)/min per 100g pulp tissue. The zone of high oxygen consumption was 68.7 micro m+/-6.9 micro m (n=24) thick. It is concluded that pulpal oxygen distribution is heterogeneous and that the odontoblast could be a major oxygen consumer within the rat incisor pulp.

Animals↗
PubMed2003

Piezo-power microdissection of mature human dental tissue.

Isolation of sufficient quantities of pure populations of odontoblasts from healthy and diseased teeth will facilitate our understanding of dentinogenesis during development and repair. Here we describe a novel Piezo-power microdissection (PPMD) technique for the isolation of pure populations of odontoblasts and pulpal tissue from formalin-fixed, paraffin-embedded, mature, healthy and carious human teeth. Odontoblasts and pulpal tissue gene expression were subsequently studied in ribonucleic acid isolated from PPMD preparations using a semi-quantitative reverse transcription polymerase chain reaction approach. Data confirmed that the genes for dentine sialophosphoprotein and Nestin are preferentially expressed in odontoblasts, whilst the genes for both collagen-1alpha and collagen-3alpha were expressed preferentially in pulpal tissue, particularly in carious samples. PPMD provides a novel and powerful approach to isolate pure populations of dental tissues and cells from fixed specimens for subsequent downstream molecular analyses.

Base Sequence↗
PubMed1984

Dental sensory receptors.

Teeth are innervated by unmyelinated sympathetic axons, and by unmyelinated and small myelinated sensory axons. Some sensory axons in teeth are terminal branches of larger parent axons, so that conduction from teeth to CNS in trigeminal nerves includes C-fiber, A-delta, and A-beta velocities. Sensory dental axons contain acetylcholine or substance P-like immunoreactivity. The sympathetic axons contain noradrenalin. Other neuropeptides may also be present, such as vasoactive intestinal peptide and serotonin. Dental axons of mature teeth of many species (man, monkey, cat, rodents, fish) are essentially the same, but continuously erupting teeth have smaller and fewer axons. Free sensory nerve endings in mature teeth are found in the peripheral plexus of Raschkow, the odontoblastic layer, the predentin, and the dentin. Free nerve endings are most numerous in those regions near the tip of the pulp horn, where more than 40% of the dentinal tubules can be innervated. Many dentinal tubules contain more than one free nerve ending. Intradentinal axons can extend as far as 0.2 mm into dentin but usually end less than 0.1 mm from the pulp. Some sensory endings also occur along pulpal blood vessels. In continuously erupting teeth nerve endings do not enter the dentin but remain within the pulp. Nerve endings in dentin are labeled by axonal transport. They are therefore as viable and active as the nerve endings in pulp. The axoplasm of the free nerve endings contains organelles typical of other somatosensory receptors. These organelles are most common in the successive beaded regions along the free nerve endings and include mitochondria, clear and dense-core vesicles, multivesicular bodies, profiles of smooth endoplasmic reticulum, and relatively few microtubules and neurofilaments. The beads can vary in size from about 0.2 to 2.0 microns and can have varying amounts of receptor organelles. The interbead axonal regions are thin and contain mainly microtubules and neurofilaments. Nerve endings are associated with companion cells after they leave the coronal nerve bundles; these companion cells include Schwann cells, fibroblasts, and odontoblasts. There is no good evidence of gap junctions or synapses between nerve endings and odontoblasts. Instead, the two cell types form appositions that have a 20-40 nm extracellular cleft and parallel apposed plasmalemmas but no unusual membrane-associated material. No special organelles occur in the odontoblastic cytoplasm at these sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2003

Calreticulin--an endoplasmic reticulum protein with calcium-binding activity is also found in the extracellular matrix.

Previous studies have reported that calreticulin (CRT), a calcium-binding and chaperoning protein, is expressed only in the endoplasmatic reticulum, nucleus and at the cell surface. In this study we clearly show that odontoblasts and predentin matrix contain CRT. To our knowledge, this is the first time CRT has been described in the extracellular matrix. The expression of CRT was studied by immunohistochemistry, ultrastructural immunocytochemistry and in situ hybridization in developing rat teeth. CRT was detected as a 59-kDa protein in rat pulp cell culture medium and dentin extracellular matrix extract by Western blotting. The presence of the protein was shown in rat odontoblasts and predentin with immunohistochemistry. At the ultrastructural level, the labeling was distributed in the rat odontoblasts, ameloblasts and predentin. Northern blotting showed the presence of CRT mRNA in rat molars, which was confirmed by in situ hybridization in odontoblasts and ameloblasts. We now present the first convincing evidence that CRT is found in extracellular matrix where it may play an important role in mineralization.

Ameloblasts↗
PubMed1998

Dentin sialoprotein, dentin phosphoprotein, enamelysin and ameloblastin: tooth-specific molecules that are distinctively expressed during murine dental differentiation.

Dentin sialophosphoprotein [designated DSPP and cleaved into dentin sialoprotein (DSP) and dentin phosphoprotein (DPP)], enamelysin and ameloblastin are each expressed in unique fashions during tooth development. It is possible that these components participate in cell differentiation and the conversion of unmineralized matrix into mineralized structures. In order to delineate the timing and the positioning of these three molecules in a physiological context, we compared their expression profiles by performing in situ hybridization experiments on consecutive sections in developing mouse tissues. Hybridization signals were uniquely detected for DSPP mRNA in odontoblasts and preameloblasts, for enamelysin mRNA in odontoblasts and in the facing ameloblast layer, and for ameloblastin mRNA in preodontoblasts, polarizing odontoblasts and ameloblasts. Immunohistochemistry showed that DSP and ameloblastin transcripts were translated into proteins that were deposited at the apical pole of the differentiated cells (odontoblasts and ameloblasts, respectively). The interrelated expression profiles found for these tooth-specific molecules illustrate the importance of a specific molecular network to initiate highly regulated processes such as cytodifferentiation and the subsequent mineralization.

Ameloblasts↗
PubMed2002

Expression of heat-shock protein 25 immunoreactivity in the dental pulp and enamel organ during odontogenesis in the rat molar.

The present immunocytochemical study reports on the expression of heat-shock protein (Hsp) 25 during odontogenesis in rat molars from postnatal 1 to 100 days. Hsp 25 immunoreactivity (IR) appeared in the immature dental mesenchymal cells and the differentiating and differentiated odontoblasts. At 30 days, the coronal odontoblasts retained intense Hsp25-IR, whereas the odontoblasts in the root and floor pulp were initially weak or negative but increased in IR in the later stages, indicating that the expression of Hsp 25 reflects the differentiation status of odontoblasts. During amelogenesis, the secretory ameloblasts were Hsp 25 immunopositive and the enamel free area (EFA) cells showed intense Hsp 25-IR when they developed a ruffled border. Ruffle-ended ameloblasts (RA) also consistently showed intense Hsp 25-IR, but smooth ended ameloblasts (SA) showed weak IR. These data suggest that Hsp 25 is related to the formation and maintenance of the ruffled border of RA and EFA cells.

Aging↗
PubMed2001

Matrix metalloproteinase-2 in dentin matrix mineralization.

In the serum-free culture medium of bovine odontoblasts we detected active gelatinolytic metalloproteinases, matrix metalloproteinase (MMP)-2 and MMP-9 (gelatinases A and B). The activity of MMP-2, in particular, appeared suddenly around day 21 in the culture, coinciding with the development of odontoblastic cell processes and the loss of alkaline phosphatase. Reverse transcriptase-polymerase chain reaction analysis of these odontoblasts demonstrated that messages of MMP-2 but not MMP-9 increased significantly between day 15 and day 21. The in vitro observation indicates that medium conditioned by these odontoblasts and containing significant amounts of MMP-2 degrades not only the collagenous substrates but also purified dentin phosphophoryn as well. We have also observed that dephosphorylated dentin phosphoprotein becomes a better substrate for casein kinase II after limited proteolysis with MMP-2. These results support our working hypothesis that MMP-2-mediated proteolytic processing is an important step in accelerating the process of dentin matrix maturation, which includes phosphorylation and subsequent mineralization. As has been suggested previously, extracellular phosphorylation of matrix proteins is an important step in biomineralization both in bone and in dentin (Mikuni-Takagaki et al., J Bone Miner Res 1995;10:231-42; Zhu et al., Biochem J 1997; 323:637-43). Our present histochemical analysis in MMP-2 knockout mice confirms the concept with the delayed formation of mineralized tissues, dentin, and bone.

Alkaline Phosphatase↗
PubMed2004

Transforming growth factor-beta 1 (TGF-beta 1) expression in normal healthy pulps and in those with irreversible pulpitis.

AIM: To evaluate the Transforming Growth Factor-beta 1 (TGF-beta 1) expression in normal healthy pulps and in those with irreversible pulpitis. METHODOLOGY: Twenty-three normal, healthy pulps were removed from mandibular third molars, and 20 pulps were retrieved from teeth with irreversible pulpitis. TGF-beta 1 was evaluated in the odontoblastic and subodontoblastic layers, in the stromal cells (fibroblasts), and in the blood vessels. TGF-beta 1 expression was determined by evaluating 500 cells in the odontoblastic and subodontoblastic layers and 500 fibroblasts in the stroma for each specimen, and counting the number of positive cells. The number of the positive vessels was evaluated in 10 high power fields (HPF). In almost all cases, the cellular positivity was cytoplasmatic. Statistical analysis was performed using Mann-Whitney U- and Student's t-tests. RESULTS: A higher expression of TGF-beta 1 was found in the odontoblastic-subodontoblastic layer of the irreversible pulpitis specimens; this difference was statistically significant (P = 0.0002). No statistically significant difference was observed between the two groups in TGF-beta 1 expression in the stromal cells (P = 0.54) or in the vascular component (P = 0.94). CONCLUSIONS: The higher and statistically significant expression of TGF-beta 1 found in the odontoblastic-subodontoblastic layer of irreversible pulpitis specimens may indicate a role for TGF-beta 1 in the dentinal repair processes after pulp inflammation.

Adolescent↗
PubMed2006

Identification of temporal and spatial expression patterns of amelogenin isoforms during mouse molar development.

Amelogenin synthesis is initiated in a restricted time frame during odontogenesis. Polypeptides translated from several alternatively spliced isoforms of amelogenin mRNA have been identified in ameloblasts and odontoblasts. Recent studies suggest that the isoforms deleting exons 6a, 6b, and 6c produce polypeptides that might exert regulatory functions governing the late stages of ameloblast and odontoblast differentiation. Herein, the spatial and temporal expression of mouse amelogenin mRNA isoforms M194, M180, M73, and M59 have been determined around the perinatal development period using splice form-specific probes. Expression levels and distribution patterns varied with developmental stage and cell location. Amelogenin mRNA expression was most prominent within the enamel organ at boundaries between cell layers, beginning at the newborn stage (PN0.5). Odontoblasts supported the expression of M73 and M59 mRNA from developmental stages PN0.5 to PN1.5 (1 d of age). In contrast, ameloblasts expressed predominantly the M180 mRNA isoform with full exon 6 but devoid of exon 4. In the enamel organ, the stratum intermediun cells supported expression of the full-length isoform, M194, including the full exon 6 and exon 4 sequences, and strikingly, expression of M180 message was inhibited. In conclusion, ameloblasts, odontoblasts, and stratum intermedium cells demonstrate selective alternative splicing patterns of the amelogenin pre-mRNA transcript.

Aging↗