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 685 records · Page 38Linked to original sources
PubMed1961

Water and myotonia in goats.

Lipid granules have been found in the cytoplasm of odontoblasts and in the odontoblastic extensions within the dentinal tubules. It is suggested that these granules represent specific activity on the part of the normal cell as well as an increase in number after injury. While they are not limited to occurrence within the vacuoles in the cytoplasm of the odontoblasts, the relationship of the granules to the vacuoles suggests that the vacuoles are also a part of the physiologic activity of the adult odontoblasts.

Animals↗
PubMed1987

Ultrastructural observations on the intraodontoblastic collagen fibrils of the mouse tooth germs.

We examined electron-microscopically and histochemically the ultrastructural features of the intraodontoblastic collagen fibrils of the mouse. These collagen fibrils were most common in secreting odontoblasts (pre-odontoblasts) of the maturating stages. In such cells they were most numerous at the peripheral zone of the Golgi apparatus, and were sometimes seen in odontoblastic processes. Intraodontoblastic collagen fibrils also had morphological variations including a banded structure enclosed by limiting membranes of vacuoles, fusion with primary lysosomes, and an electron-dense material covering with a structure that was not banded. Study of acid phosphatase activity showed that these structural changes were caused by the degradation of intraodontoblastic collagen fibrils by lysosomes. The results of studies of the permeation of lanthanum nitrate and the alkaline phosphatase reaction showed that these collagen fibrils were separate from the extracellular matrix and that there was no phagocytosis of the odontoblasts.

Acid Phosphatase↗
PubMed1987

Immunocytochemical localization of osteocalcin in developing rat teeth.

Osteocalcin was purified by gel chromatography from a crude extract obtained after decalcification of rat incisors. The apparent molecular weight, as determined by 5-15% SDS-polyacrylamide gel electrophoresis, was 18,000, and amino acid analysis revealed 60 gamma-carboxyglutamic acid residues per 1000. Antisera against osteocalcin, raised in rabbits, reacted specifically with osteocalcin when investigated by immuno-electroblotting of dentin crude extract. 4-micron cryosections of formaldehyde-fixed tooth germs showed positive immunocytochemical staining for osteocalcin in dentin and odontoblasts. The staining of the mantle dentin at the coronal sides of the tooth germs was more intense than that of the adjacent circumpulpal dentin, while the odontoblasts involved in the formation of mantle dentin showed stronger immunoreactivity than did odontoblasts involved in circumpulpal dentin formation. This marked difference was not observed on the root sides of the tooth germs. In 1-micron cryosections, osteocalcin immunoreactivity was found evenly distributed throughout the entire cell body, with the exception of the Golgi region, which was less intensely stained, while the nucleus and the cell process were negative. The positive staining reaction with anti-osteocalcin antiserum was found in dentin from the very onset of its formation in the fetus. In conclusion, our results demonstrate the presence of osteocalcin in odontoblasts and dentin. Its immunocytochemical localization may be compatible with a distinct role in early dentinogenesis.

Animals↗
PubMed1992

Expression of type I collagen pro-alpha 2 chain mRNA in adult human permanent teeth as revealed by in situ hybridization.

The expression of the gene COL1A2, coding for the pro-alpha 2 chain of type I pro-collagen, was analyzed in fully developed human permanent teeth. The teeth were fixed with formalin, demineralized with EDTA for about ten weeks, and embedded in paraffin. Pro-alpha 2(I) mRNA was localized in the sections by in situ hybridization, with use of [35S)]-labeled single-stranded RNA probes. The amount of mRNA for pro-alpha 2(I) collagen chain, as indicated by the relative densities of silver grains and the grain counts per cell in autoradiography, was high in odontoblasts, whereas in pulpal fibroblasts it was low. High levels of pro-alpha 2(I)mRNA expression were also present in those odontoblasts which had elaborated new dentin matrix in response to dental caries. Expression in the periodontal ligament, including the cementoblast layer, was slightly stronger than that in odontoblasts. The intense expression of pro-alpha 2(I) mRNA in odontoblasts of adult teeth suggests that even after the completion of primary dentin formation, they continue to synthesize heterotrimeric type I collagen molecules. Cell type-specific differences in the expression of pro-alpha 2(I) mRNA imply that type I collagen probably plays a major role in the regulation of the structure and function of dental tissues. Finally, in situ hybridization enabled pro-alpha 2(I) collagen mRNA to be detected in tissue sections even after prolonged demineralization, and thus it proved to be a valuable technique for analysis of gene expression in adult dental tissues, as shown here for COL1A2.

Adult↗
PubMed1994

Stage-specific expression of decapentaplegic-Vg-related genes 2, 4, and 6 (bone morphogenetic proteins 2, 4, and 6) during human tooth morphogenesis.

Members of the decapentaplegic-Vg-related (DVR) gene family are diffusible signaling molecules regulating inductive tissue interactions during vertebrate development. Expression of DVR/bone morphogenetic protein (BMP) 2, 4, and 6 was studied in human fetal teeth. Sequential morphogenetic stage-specific studies of DVR/BMP 2 and 4 mRNA expression by in situ hybridization revealed transcripts for DVR/BMP 4 during compaction of the dental mesenchyme. In contrast, DVR/BMP 2 mRNA appeared later during tooth development and was located in differentiated cells (odontoblasts). These results were confirmed by reverse-transcription polymerase chain reaction (RT-PCR), which detected DVR/BMP 2 and 4 mRNA in human tooth-germ samples. DVR/BMP 6 protein was distributed in the early dental epithelium and, later, in pre-odontoblasts and odontoblasts, where it remained during dentin formation. These results suggest that DVR/BMP 4 is involved in the early tooth morphogenesis. DVR/BMP 6 may, in particular, be implicated in epithelial-mesenchymal interactions controlling cytodifferentiation. DVR/BMP 2 and 6 may also be involved in odontoblast secretory function. The results suggest that members of the DVR gene family may play regulatory roles during human tooth development.

Base Sequence↗
PubMed1996

Immunohistochemical localization of HLA-DR-positive cells in unerupted and erupted normal and carious human teeth.

Class II major histocompatibility complex (MHC) antigen-expressing cells are generally associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, normal, and carious human teeth to clarify when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically by means of HLA-DR monoclonal antibody. In the pulp of unerupted developing teeth, numerous HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer, with slender cytoplasmic processes extending into the layer. Superficial caries lesions caused an aggregation of HLA-DR-positive cells in dental pulp corresponding to the lesion. In teeth with deeper caries lesions, this aggregation of cells expanded to include the odontoblast layer. Also noted were HLA-DR-positive cells lying along the pulp-dentin border, with cytoplasmic processes projecting deep into the dentinal tubules, where they co-localized with odontoblast processes. These findings suggest that: (1) human dental pulp is equipped with immunologic defense potential prior to eruption; (2) in the initial stage of caries infection, an immunoresponse mediated by class-II-expressing cells is initiated in human dental pulp; and (3) HLA-DR-positive cells trespass deep into dentinal tubules as the caries lesion advances.

Adolescent↗
PubMed1996

An in vitro model of human dental pulp repair.

Pulp tissue responds to dentin injury by laying down reactionary dentin secreted by existing odontoblasts or reparative dentin elaborated by odontoblast-like cells that differentiated from precursor cells in the absence of inner dental epithelium and basement membrane. Furthermore, growth factors or active dentin matrix components are fundamental signals involved in odontoblast differentiation. In vitro, dental pulp cells cultured under various conditions are able to express typical markers of differentiation, but no culture system can re-create pulp response to dentin drilling. This paper reports the behavior of thick slices from human teeth drilled immediately after extraction and cultured from 3 days to 1 month. Results show that the damaged pulp beneath the cavity is able to develop, in vitro, some typical aspects correlated to tissue healing, evidenced by cell proliferation (BrdU-positive cells), neovascularization (positive with antitype-IV collagen antibodies), and the presence of functional (3H proline-positive) cuboidal cells close to the injured area. After 30 days of culture, elongated spindle-shaped cells can be seen aligned along the edges of the relevant dentin walls, whereas sound functional odontoblasts are well-preserved beneath healthy areas. This tissue recovery leads us to believe that such a culture model will be a useful system for testing factors regulating pulp repair.

Adolescent↗
PubMed2002

The localization of matrix metalloproteinase-20 (MMP-20, enamelysin) in mature human teeth.

MMP-20 (enamelysin), the matrix metalloproteinase family member discovered in the enamel organ, has also been detected in odontoblasts during dentin formation. We studied the presence and localization of MMP-20 in mature human teeth in health and disease. In immunohistochemistry, MMP-20-positive staining was observed most intensively in the radicular odontoblastic layer and also in dilated dentinal tubuli of caries lesions. By Western blotting, MMP-20 was detected in odontoblasts and pulp tissue of both sound and carious teeth, in dentinal fluid and dentin of sound teeth, but not in soft carious dentin. We conclude that MMP-20 produced during primary dentinogenesis is incorporated into dentin and may be released during caries progression. The main cellular source of MMP-20 in the dentin-pulp complex is the odontoblasts, which secrete MMP-20 into the dentinal fluid.

Blotting, Western↗
PubMed1994

In situ localization and chromosomal mapping of the AG1 (Dmp1) gene.

Dentinogenesis is being used as a model for understanding the biomineralization process. The odontoblasts synthesize a structural matrix comprised of Type I collagen fibrils which define the basic architecture of the tissue. The odontoblasts also synthesize and deliver a number of dentin-specific acidic macromolecules into the extracellular compartment. These acidic macromolecules may be involved in regulating the ordered deposition of hydroxyapatite crystals within the matrix. AG1 is the first tooth-specific acidic macromolecule to have been cloned and sequenced. To identify which cells of the rat incisor pulp/odontoblast complex were responsible for synthesis of AG1, in situ hybridization was used. Digoxigenin labeled sense and anti-sense AG1 riboprobes were prepared. The AG1 mRNA was found to be expressed in the mature secretory odontoblasts. Neither pulp cells nor pre-odontoblasts showed any staining with the anti-sense probes. Chromosomal localization studies placed the AG1 gene on mouse chromosome 5q21, in tight linkage with Fgf5. AG1 has been renamed Dmp1 (dentin matrix protein 1) in accordance with present chromosomal nomenclature. Mouse 5q21 corresponds to the 4q21 locus in humans. This is the locus for the human tooth mineralization disorder dentinogenesis imperfecta Type II (DI-II). These data suggest that the Dmp1 gene is involved in mineralization and is a candidate gene for DI-II.

Animals↗
PubMed1996

Immunolocalization of vitamin D receptor and calbindin-D28k in human tooth germ.

The role of vitamin D in ameloblasts and odontoblasts has been studied experimentally in rodents. Dental dysplasias have also been reported in clinical studies of children with rickets. Vitamin D acts via a nuclear receptor which binds the major metabolite, 1,25-dihydroxyvitamin D3, and positively or negatively controls the expression of specific genes. The most extensively studied markers of 1,25-dihydroxyvitamin D3 action are calbindin-D9k, calbindin-D28k, and osteocalcin. Therefore, to study in more detail the potential role of 1,25-dihydroxyvitamin D3 in human dental development, 1,25-dihydroxyvitamin D3 receptor (VDR) was localized by immunofluorescence in forming teeth (8-26 wk of gestation). Calbindin-D28k was also mapped by immunoperoxidase in antenatal and postnatal forming and formed teeth. VDR were detected in both dental epithelium and mesenchyme of bud, cap, and bell stages of tooth germs. Nuclei of overtly differentiated ameloblasts and odontoblasts were also immunostained. Calbindin-D28k was present in differentiated ameloblasts and odontoblasts. The presence of VDR and calbindin-D28k in ameloblasts and odontoblasts suggests that 1,25-dihydroxyvitamin D3 may contribute to the regulation of enamel and dentin formation, as classically reported for bone formation. Finally, the early appearance of VDR supports the concept that 1,25-dihydroxyvitamin D3 may also control forward stages of tooth crown development in humans.

Ameloblasts↗
PubMed1996

In situ investigation of vitamin D receptor, alkaline phosphatase, and osteocalcin gene expression in oro-facial mineralized tissues.

The aim of this study was to investigate the expression pattern of 1, 25-dihydroxyvitamin D3 receptor (VDR) and vitamin D-responsive gene expression during the steps of hard tissue formation in oro-facial development. In situ hybridization of VDR, alkaline phosphatase, and osteocalcin transcripts was performed in the mandibles of growing rats. Osteoblasts were used as the internal positive control for in situ detection of VDR messenger RNAs. Transcripts were present throughout the stages of differentiation and in differentiated osteoblasts and osteocytes, and showed some anatomical specificities in their developmental expression pattern. In dental tissues, VDR was strongly expressed in the inner dental epithelium at the beginning of the presecretion stage and, after a transient decrease at the end of the presecretion stage, in secretion stage ameloblasts. VDR was continuously expressed in epithelial supraameloblastic cells. During dentin formation, VDR was mainly present in subodontoblastic cells and was down-regulated during the terminal differentiation of odontoblasts. In these cells, VDR expression appeared to be induced by 1, 25-dihydroxyvitamin D3 injection. These data confirm that VDR is expressed in cells directly involved in mineralized tissue formation: ameloblasts, odontoblasts, and osteoblasts. Furthermore, they extend the idea of vitamin D sensitivity to cells that are not directly involved in this process: supraameloblastic, subodontoblastic, and osteoprogenitor cells. The differential expression pattern of VDR in odontoblasts and osteoblasts together with the similarity in the expression of potential vitamin D-responsive genes (osteocalcin in odontoblasts and osteoblasts, and alkaline phosphatase in osteoprogenitor and subodontoblastic cells) suggest the existence of a tissue specificity for the genomic action of 1, 25-dihydroxyvitamin D3, which may involve co-operation with additional nuclear factors.

Alkaline Phosphatase↗
PubMed1991

Differential expression of type I and type III collagen genes during tooth development.

Collagen gene expression during mouse molar tooth development was studied by quantitative in situ hybridization techniques. Different expression patterns of type I and type III collagen mRNAs were observed in the various mesenchymal tissues that constitute the tooth germ. High concentration for pro-alpha 1(I) and pro-alpha 2(I) collagen mRNAs were found within the osteoblasts. We found that the cellular content of type I collagen mRNAs in the odontoblasts varies throughout the tooth formation: whereas mRNA concentration for pro-alpha 1(I) collagen decreases and that of pro-alpha 2(I) increases, during postnatal development. Moreover, different amounts of pro-alpha 1(I) and pro-alpha 2(I) collagen mRNAs were observed in crown and root odontoblasts, respectively. Type III collagen mRNAs were detected in most of the mesenchymal cells, codistributed with type I collagen mRNAs, except in odontoblasts and osteoblasts. Finally, this study reports differential accumulation of collagen mRNAs during mouse tooth development and points out that type I collagen gene expression is regulated by distinct mechanisms during odontoblast differentiation process. These results support the independent expression of the collagen genes under developmental tissue-specific control.

Animals↗
PubMed1998

Identification of a novel isoform of mouse dentin matrix protein 1: spatial expression in mineralized tissues.

Dentin matrix protein 1 (Dmp1) is an acidic phosphoprotein first identified by cDNA cloning from a rat tooth library. Northern blot hybridization of a variety of tissues detected Dmp1 mRNAs only in odontoblasts, suggesting that this protein was odontoblast specific. In situ hybridization studies showed expression of Dmp1 in odontoblasts with transient expression in secretory ameloblasts. The purpose of this study was to isolate and characterize a mouse Dmp1 cDNA and determine its spatial expression pattern related to other mineralizing tissues. A mouse molar cDNA library was screened with a 32P-labeled Dmp1 polymerase chain reaction amplification product in order to isolate a full-length clone. DNA sequence analysis of the largest mouse Dmp1 cDNA (2802 base pairs [bp]) revealed an open reading frame of 1509 nucleotides encoding a 503 amino acid protein with a single polyadenylation signal. Comparison with rat and bovine Dmp1 sequence showed high homology and the identification of a 45 bp (15 amino acid) insert, representing an alternative spliced mRNA. This 45 bp segment was shown to represent a small exon by DNA analysis of a mouse genomic Dmp1 clone. In situ hybridization studies revealed a much broader Dmp1 tissue expression pattern than previously reported. Dmp1 transcripts were detected in the odontoblast and ameloblasts, osteoblasts, and cementoblasts. Our data indicate that Dmp1 is alternatively spliced, and the primary full-length transcript contains a 45 bp insert which is encoded by a small exon. Therefore, Dmp1 is not a tooth-specific protein but rather is expressed in a number of mineralizing tissues including enamel, bone, and cementum.

Ameloblasts↗
PubMed1982

Morphological research on the sensitivity of dentin.

In order to elucidate the mechanism of dentin sensitivity, the ultrastructure, distribution and organization of nerve fibers in the pulpodentinal border zone in the teeth of young human subjects were investigated by means of silver impregnation and electron microscopy. The nerve fibers in this zone were classified into four types by the location of their terminals and pattern of their ramification: the marginal pulpal nerve fibers, the simple predentinal nerve fibers, the complex predentinal nerve fibers and the dentinal nerve fibers. The nerve fibers reached no further than 100 microns from the odontoblast-predentinal border. The nerve fibers terminated exclusively as free endings, and they were thought to conduct the sense of pain from the corresponding zone. The endings of the predentinal or dentinal nerve fibers were mostly located adjacent to the odontoblastic processes, and this appeared to be a reasonable position for these endings to actively receive the changes in the shape of the processes. The odontoblastic process and the nerve ending associated with it can be considered to be functionally a mechanoreceptive complex. In this sense these free nerve endings might be placed in a group different from the free nerve endings in the inner pulp. The mechanoreceptive complex probably plays a central role in the mechanism of dentin sensitivity. It is suggested that stimuli to dentin first produce the deformation or movement of the odontoblastic processes; these mechanical changes are transmitted to the nerve endings, and the dentin sensitivity occurs.

Axons↗
PubMed1984

Membrane structures in the pulp-dentin border zone. A freeze-fracture study of demineralized human teeth.

The membrane morphology of cells in the pulp-dentin border zone in human teeth was scrutinized by means of the freeze-fracture technique. The tissue was fractured and replicated after mild demineralization in Na-EDTA. This procedure did not seem to influence the preservation of the tissue significantly. The odontoblastic cell bodies and their long processes lying within the predentinal and dentinal tubules were exposed. The technique made it possible to analyze the structural features of the apical part of the odontoblastic layer, including the 'terminal bar' region. This area exhibited large, irregularly shaped gap junctions. In some regions clusters of many small membranous pits or caveolae apparently representing pinocytotic vesicles were seen. The odontoblastic process displayed membrane protuberances projecting outward and abutting the inner tubular wall. In the predentinal and the adjacent dentinal regions, fine-caliber fibers (approximately 0.1-0.4 micron in diameter), presumably nerves, appeared in intimate relationship with the odontoblastic cell processes. At these sites the cell membrane displayed aggregations of membrane-associated particles, presumably gap junctions.

Adolescent↗
PubMed1995

Responses of immunocompetent cells to cavity preparation in rat molars: an immunohistochemical study using OX6-monoclonal antibody.

Responses of immunocompetent cells, especially class II major histocompatibility complex (MHC) antigen-expressing cells, were investigated after cavity preparation in the erupted upper first molar teeth of rats, by immunohistochemistry using OX6-monoclonal antibody. In control teeth, OX6-immunopositive cells were predominantly located beneath the odontoblast layer in the dental pulp. Cavity preparation caused an acute edematous reaction between the injured odontoblasts and predentin, and most of OX6-immunopositive cells in the affected site shifted away from the pulp-dentin border. After 12-24 hours, many OX6-immunopositive cells accumulated along the pulp-dentin border and extended their cytoplasmic processes into the exposed dentinal tubules. After 72 hours, newly differentiated odontoblasts replaced the degenerated odontoblasts, and few OX6-immunopositive cells remained along the pulp-dentin border. Our data suggest that some of the class II MHC antigen-expressing cells in the dental pulp participate in the initial defense reaction and presumably serve as a biological sensor for the external stimuli arriving through the exposed dentinal tubules.

Animals↗
PubMed1995

Dentin matrix proteins and dentinogenesis.

The precise mechanisms involved in dentinogenesis are not understood; however, the information to date suggests that a number of highly controlled extracellular events are involved. Mature odontoblasts secrete collagen at the cell border into predentin. They synthesize and secrete other non-collagenous proteins (NCPs) at the mineralization front, possibly through odontoblastic processes. A collagen-NCP complex is formed at the predentin-dentin border and apatite crystal initiation and growth takes place. One of the research needs is to uncover the nature of this dentin collagen-NCP complex and to understand how it controls mineralization. At least three dentin specific NCPs are known: phosphophoryn(s), dentin sialoprotein (DSP) and AG1 (Dmp1). Other macromolecules are commonly made by osteoblasts and odontoblasts and participate in bone and dentin formation. Some progress in understanding dentin mineralization has been gained by focusing upon the role of phosphophoryns. These highly phosphorylated proteins are secreted at the mineralization front, where a small portion binds in the gap region of type I collagen fibrils. This portion of phosphoproteins probably initiates formation of plate-like apatite crystals. Additional phosphoryns in higher concentrations bind to the growing apatite crystals and slow their growth, possibly influencing their size and shape. Other areas which need careful investigations are those involving the mechanisms involved in odontoblast differentiation, how the synthesis of the dentin specific NCPs is controlled and the precise roles of these macromolecules in dentinogenesis. Future experimentation will focus on the gene structures for these NCPs and the mechanisms of tissue specific gene regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Apatites↗
PubMed1999

Vimentin localisation in tooth germ cells of two marsupial species, the northern brown bandicoot, Isoodon macrourus, and the brushtail possum, Trichosurus vulpecula.

In marsupial teeth, long cellular processes from ameloblasts and odontoblasts are found in the developing enamel and dentinal tubules, respectively. It has been suggested that the odontoblast cytoskeleton plays a role in the dentinal tubule formation of rat. To understand the role of the cytoskeleton in the blast cells, the location of vimentin and cytokeratin in the tooth germ of the bandicoot and the possum was examined using immunohistochemical techniques. Vimentin was detected in differentiating and secretory ameloblasts and may be involved with the secretion of fibronectin. Vimentin labelling was much weaker and irregular in cells of the outer enamel epithelium, the stellate reticulum and the stratum intermedium. Dentinal tubules, odontoblasts and dental papilla fibroblasts also stained positively for vimentin. Positive staining for cytokeratin was observed in all cells in the enamel organ but not in the enamel and dentinal tubules or the cells of the dental papillae. The presence of vimentin in the dentinal tubules indicated that the odontoblast processes in these tubules were still active and they extended to near the enamel-dentin junction. In conclusion, the presence of vimentin in tooth germ cells suggests that it may be involved in the formation of enamel tubules in marsupials.

Animals↗