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At least 127 records · Page 7Linked to original sources
PubMed2005

Evidence for inclusion of a segment of Escherichia coli genomic DNA in bovine tooth germ mRNA encoding salivary proline-rich protein P-B.

In the course of cloning of bovine cDNA for proline-rich protein (PRP) P-B from bovine tooth germ cDNA, we found that one clone with 662 bp contained a 5'-terminal 393 bp (1-393 bp) sequence essentially identical to that of human P-B cDNA (154-546 in D29833) and bovine P-B cDNA (1-356 bp in AB192573) and a sequence of 233 bp (394-626 bp) highly homologous to the segment of E. coli K12 genomic DNA (365511-365744 in NC000913). Although the latter sequence is contained in the vector pT7Blue, which we used, our results show that this chimeric structure in bovine tooth germ P-B cDNA is not an artifact formed during the cloning process, but intrinsic to the bovine genome since the chimeric structure was detected in bovine tooth germ and bovine genomic DNA.

Animals↗
PubMed1984

Histology, innervation and radiographic appearance of fetal rat tooth germs developing in oculo.

Rat molar and incisor tooth germs from gestational days 18-21 were homologously grafted to the anterior eye chamber of adult recipients. The fetal tooth transplants survived and grew considerably in the eye, attached to and vascularized from the anterior surface of the host iris. Grafts were examined histologically and compared with in situ controls after up to 6 months in oculo. Radiographic examinations of the grafts showed a normal rate of mineralization and a distinct enamel/dentin border after intraocular development. The size of the tooth grafts was somewhat smaller than in situ but the grafted teeth attained a form much resembling in situ incisors and molars. Light microscopy revealed a regular dentin and predentin, a distinct dentin/enamel border and a well innervated and vascularized pulp. No degenerative changes in dentin or enamel layers could be found in long-term grafts (6 months). Thus, intraocular tooth grafts in rats develop many histologic and anatomic features typical of normal teeth, emphasizing the importance of intrinsic regulatory mechanisms in tooth development.

Animals↗
PubMed1992

[Distribution of bone morphogenetic protein in human bone and tooth germs: analysis of specificity of monoclonal antibody against bone morphogenetic protein].

A cell strain stably secreting monoclonal antibody against BMP was obtained by hybridoma technique. The monoclonal antibody specifically reacted with the cells of human bone and tooth germs on paraffin embedded tissue sections. Immunohistochemical staining shows that BMP is distributed along collagen fibres in normal bone, also exist in osteoid tissue of new bone, in osteoblasts and in the cells of bone marrow. BMP may be found in human tooth germs such as in predentin, in the cells of outer and inner enamel epithelium, in the cells of dental sac generating alveolar bone. The results demonstrate that generation and growth of human bone and development of tooth germs have relation to BMP. The results at the molecular level prove that some antigenic determinants of human and bovine BMP are the same. BMP function activity inhibition test suggests that this antibody may block the function group of BMP. The ability of the monoclonal antibody to detect antigen and to inhibit generation of new bone makes it potentially useful in purification of BMP and in treating osteosarcoma and other bone tumors.

Animals↗
PubMed1985

Effect of 1-p-bromotetramisole on phosphatases in neonatal hamster bone and tooth germs at different pH.

This study was designed to compare the various phosphatases and pyrophosphatases in bone with those in developing teeth. Moreover the alkaline phosphatase inhibitor 1-p-bromotetramisole (1-pBTM) was assessed for its ability to discriminate between the several phosphatase activities. Enzyme activities were determined over the pH range 3.50 to 11.25 in homogenates of calcifying hamster tibiae, and whole tooth germs using p-nitrophenyl-phosphate (pNPP) and pyrophosphate (PPi) as substrates. Characterization of alkaline phosphatase inhibition with 1-pBTM showed that in tooth germs the pI50 values of 1-pBTM for whole tooth germs, ectodermal and mesenchymal phosphatases were identical (pI50 = 5.36), which was slightly but significantly lower than that for bone alkaline phosphatase (pI50 = 5.64). In bone, two pNPP-ase activities were found with optima at pH 5.5 and pH 10.3 respectively. The alkaline phosphatase activity was completely inhibited by 10(-4) M 1-pBTM. Inhibition of the acid phosphatase was incomplete. With PPi as substrate, three activities were found with optima at pH 4.8, 7 and 8.7 respectively. All these PPi-ase activities were strongly inhibited by 1-pBTM in developing teeth, only one phosphatase activity was found, which exhibited an alkaline pH (10.3) optimum with both substrates. This activity was inhibited by 1-pBTM with both substrates although the effect on pNPP-ase activity was more marked. From these results we conclude that in bone there are insufficient differences in the extent of inhibition by 1-pBTM to distinguish between the various phosphatase activities when more physiological substrates such as pyrophosphate (PPi) are used.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Nitrophenylphosphatase↗
PubMedDate not supplied

Effect of alpha, alpha'-dipyridyl on the basement membrane of tooth germs in vitro.

Dipyridyl inhibits the morphogenesis of tooth germs, but the germs recover when transferred to control medium. In this study, the effect of dipyridyl on basement membrane was investigated in vitro. The basal lamina was always present, but the subjacent collagen fibrils disappeared in the presence of dipyridyl and reappeared during recovery in control medium.

2,2'-Dipyridyl↗
PubMed2003

Fgf-2 regulates enamel and dentine formation in mouse tooth germ.

We examined the effects of basic fibroblast growth factor (FGF-2) on cultured lower molar tooth germ at the differentiative (bell) stage. Although FGF-2 has been detected in odontogenesis, its roles in biological activities, such as cell proliferation, differentiation and extracellular matrix mineralization are unclear. We assayed mRNA levels of the differentiation markers, dentine sialophosphoprotein (DSPP), amelogenin and alkaline phosphatase (ALP) using reverse transcription-polymerase chain reaction (RT-PCR), and histological methods. Tooth germs dissected from 17-day-old embryonic mice were cultured for 4 days with either recombinant human FGF-2 or specific antisense phosphorothioate oligodeoxynucleotide (antisense ODN) for FGF-2. Exogenous FGF-2 decreased the gene expression of differentiation markers in molars at the bell stage. Abrogation of endogenous FGF-2 by antisense ODN increased the gene expression of differentiation markers, and also significantly enhanced enamel and dentine formation. This histological change was recovered by adding exogeneous FGF-2. These findings suggest that FGF-2 at the bell stage regulates cell differentiation and matrix secretion.

Alkaline Phosphatase↗
PubMed1979

The effect of protein-energy malnutrition on the growth of tooth germs in newborn rats.

The effect of protein-energy malnutrition on the growth of molar and incisor tooth germs was studied. Significant differences were found between control and malnourished groups in the weights and calcium contents of both tooth germs. The data point to the importance of the effect of nutrient deficiency on the critical growth period of an oral structure.

Age Factors↗
PubMed1981

Calmodulin-like activity in a mineralising tissue: the rat molar tooth germ.

Calmodulin, a calcium binding protein, has been implicated in the regulation of many calcium-dependent biological processes. Since calcium has an important role in hard tissue genesis, both at intra- and extracellular levels, we anticipate that calcium binding proteins may modulate this process. The present study investigated a mineralising tissue, the rat molar tooth germ, to determine the presence of calmodulin-like activity. A heat-treated cell-free extract of tooth germs provided enhancement of Ca2+-dependent Mg2+-ATPase and 3':5'-nucleotide phosphodiesterase activity. No enhancement occurred in the absence of calcium or in the presence of trifluoperazine. SDS-polyacrylamide gel electrophoresis of this extract revealed a protein band of approximately 18,000 mol. wt. These findings indicate the presence of calmodulin-like activity in rat molar tooth germs and support the proposal that calcium and calcium binding proteins, in particular calmodulin, have a major regulatory role in the biology of mineralising tissues.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2006

[A histological innovative study of Balb/c mouse tooth germ transplanted to nude mouse in vivo].

PURPOSE: To observed the changes of the developed mouse's dental germs after transplanting into nude mouse and find some theoretical foundation for establishing an innovative experimental model. METHODS: Eight tooth germs from four 5th day postnatal Balb/c mice were transplanted to the back muscles of the adult nude mice. At seventh and fourteenth day after grafting, the germs were collected, fixed, demineralized, dehydrated, and embedded in wax. Serial sections of 5 microm thick were made following the routine methods, stained with haematoxylin-eosin dying solution, and observed under a light microscope. The mandibular first molars were taken out from the 12th and 19th day postnatal mouse. Serial sections of 5 microm thick were made following the routine methods, then compared with the germs after graft. RESULTS: All implantations were located in the superficial muscles with abundant capillary vessels. The dental germs could further developed after grafting under the microscope, but slower than dental germs self-development. The layer of dentin was thin, plenty of dentin with disorganized dentin tubule formed after grafting. Although the location of Hertwig's epithelial root sheath hardly moved, the roots developed further. The floor of pulp chamber could form and the pulp chambers were shrinking. The degree of calcification in the area of root increased very clearly. The inflammatory reaction was found at 7th day while hardly noted at 14th day after grafting. CONCLUSIONS: It suggests that late development of mouse tooth germs could further develop after heterotopic transplantation within the superficial muscles of the nude mouse. This model is useful for study of tooth root development in short time.

Animals↗
PubMed2001

Localization of activated caspase-3-positive and apoptotic cells in the developing tooth germ of the mouse lower first molar.

This study examined the immunohistochemical detection of activated caspase-3, and its association with apoptosis, during tooth morphogenesis of the mouse lower first molar. The distribution of cells positive for caspase-3 closely corresponded with the localization of the terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate-biotin nick end labelling (TUNEL)-positive apoptotic cells through the developmental course of tooth germs from embryo day 12 (E12) to E19, thus showing that the apoptosis occurring in the developing odontogenic tissue was induced by the activation of the caspase family. The specific distribution pattern of apoptotic cells in the developing odontogenic epithelial tissue from the initiation (E12) of tooth germ to the completion of tooth crown morphology (E19) also suggests that apoptotic events are related not only to a deletion of functionally suspended cells, but also participate in initiation and the completion of tooth morphogenesis. Electron microscopic examination revealed that apoptotic cells were present in the primary enamel knot, and these apoptotic cells were phagocytized by neighbouring odontogenic epithelial cells, thus indicating the prompt disposal of any dead cells by epithelial cells.

Animals↗
PubMed1984

Effect of 1-p-bromotetramisole on mineralization of hamster tooth germs in vitro: a light and electron microscopic study.

In culture, 10(-3)M 1-p-bromotetramisole (1-pBTM) inhibited mineralization of in vitro secreted enamel matrix in two-day old neonatal hamster first maxillary molar tooth germs. In contrast, in control tooth germs cultured without the inhibitor, new enamel and dentin matrices were secreted and subsequently mineralized in vitro. It is suggested that the arrested enamel matrix mineralization in vitro is a result of reduced phosphate uptake due to alkaline phosphatase inhibition by 1-pBTM. In addition, 1-pBTM induced accumulation of secretory granules in odontoblasts and ameloblasts, but not in the other cells. This is probably a specific effect of the inhibitor on these cells due to alkaline phosphatase inhibition.

Alkaline Phosphatase↗
PubMed2005

The dentin sialoprotein (DSP) expression in rat tooth germs following fluoride treatment: an immunohistochemical study.

UNLABELLED: Fluoride is known to alter expression of dentin matrix proteins and affect their posttranslational modifications. OBJECTIVE: The objective of our study was to examine dentin sialoprotein (DSP) expression in the early and late bell stages of development of the first molar tooth germs in rats treated with fluoride. DESIGN AND METHODS: Pregnant dumps were divided into three groups. They were fed a standard diet and from the fifth day of pregnancy, each group received either tap water (with trace amounts of fluoride), tap water with a low concentration of fluoride, or tap water with a high concentration of fluoride. Changes in DSP expression and distribution were visualized by immunohistochemistry. RESULTS: Immunoreactivity for DSP was detected in the cervical regions of the early bell stage in tooth germs of the 1-day-old animals. The earliest reaction was visible in the control group and the group supplemented with the low fluoride concentration (F(L)) but not in the group supplemented with the high fluoride concentration (F(H)). In early bell stages across all experimental groups, the immunoreactivity to DSP was observed in the cusp tip regions and was localized to preameloblasts, young and mature odontoblasts, dental pulp cells, predentin, and dentin. Generally, more intense positive staining for DSP was detected in animals supplemented with the high fluoride concentration. In the late bell stage found in the 4-day-old control group and the group supplemented with the low fluoride concentration, immunoreactivity for DSP was less intense compared with younger animals. However, immunoreactivity was greater in the group treated with the high dose of fluoride. In this group, the positive immunostaining for DSP, especially in young ameloblasts, was prolonged and relatively strong. CONCLUSIONS: Fluoride supplementation causes changes in the developmental pattern of DSP expression and its distribution in rat tooth germs.

Administration, Oral↗
PubMedDate not supplied

In situ expression of heat shock proteins, Hsc73, Hsj2 and Hsp86 in the developing tooth germ of mouse lower first molar.

This study examined the detailed gene expression pattern of three different heat shock proteins (HSPs), Hsc73, Hsj2, and Hsp86, by means of an in situ hybridization method. Hsc73, Hsj2, and Hsp86 were shown in our previous study to be differentially expressed in the mouse embryonic mandible at day 10.5 (E10.5) gestational age. These HSP genes showed similar expression patterns during development of the mouse lower first molar. HSPs-expressing cells were widely distributed in both the epithelial and underlying ectomesenchymal cells at E10.5, and then were slightly localized at E12 in an area where the tooth germ of the lower first molar is estimated to be formed. A strong expression of HSPs was observed in the tooth germ at E13.5. At the cap stage, HSPs were expressed in the enamel organ and dental papilla. At the bell stage, HSPs were distinctly expressed in the inner enamel epithelium and dental papilla cells facing the inner enamel epithelial layer, which later differentiate into ameloblasts and odontoblasts, respectively. This study is the first report in which Hsc73, Hsj2, and Hsp86 were distinctly expressed in the developing tooth germ, thus suggesting these HSPs are related to the development and differentiation of odontogenic cells.

Animals↗
PubMed1995

Detection of bromo-deoxyuridine- and proliferating cell nuclear antigen-immunoreactivities in tooth germ.

The development of antibodies to cell cycle-related antigens provides the basis for immunochemical studies on cell kinetics. Bromo-deoxyuridine (BrdU) incorporated by S-phase traversing cells is an exogenous marker of replicating cells, whereas proliferating cell nuclear antigen (PCNA) is an endogenous marker of replicating cells. We have applied monoclonal antibodies to BrdU and PCNA to study cell kinetics in tooth germ by immunohistochemistry and flow cytometry. BrdU-antibody reacted only with S phase-traversing cells in pulse-labelling experiments, whereas PCNA-antibody reacted with G1, S and G2-M phases traversing cells. Although the number of PCNA-positive cells largely exceeded the number of BrdU-labelled cells, the pattern distribution of immunoreactive cells was similar using BrdU- and PCNA-antibodies as revealed by immunohistochemistry. The use of PCNA-antibody allowed the detection of proliferating cells also in human tooth germ. It is suggested that combined identification of BrdU and PCNA on one side and growth factors, oncoproteins or differentiation markers on the other side may constitute a useful approach to understand the mechanisms of cell differentiation in tooth germ.

Animals↗
PubMed2006

The HOX genes are expressed, in vivo, in human tooth germs: in vitro cAMP exposure of dental pulp cells results in parallel HOX network activation and neuronal differentiation.

Homeobox-containing genes play a crucial role in odontogenesis. After the detection of Dlx and Msx genes in overlapping domains along maxillary and mandibular processes, a homeobox odontogenic code has been proposed to explain the interaction between different homeobox genes during dental lamina patterning. No role has so far been assigned to the Hox gene network in the homeobox odontogenic code due to studies on specific Hox genes and evolutionary considerations. Despite its involvement in early patterning during embryonal development, the HOX gene network, the most repeat-poor regions of the human genome, controls the phenotype identity of adult eukaryotic cells. Here, according to our results, the HOX gene network appears to be active in human tooth germs between 18 and 24 weeks of development. The immunohistochemical localization of specific HOX proteins mostly concerns the epithelial tooth germ compartment. Furthermore, only a few genes of the network are active in embryonal retromolar tissues, as well as in ectomesenchymal dental pulp cells (DPC) grown in vitro from adult human molar. Exposure of DPCs to cAMP induces the expression of from three to nine total HOX genes of the network in parallel with phenotype modifications with traits of neuronal differentiation. Our observations suggest that: (i) by combining its component genes, the HOX gene network determines the phenotype identity of epithelial and ectomesenchymal cells interacting in the generation of human tooth germ; (ii) cAMP treatment activates the HOX network and induces, in parallel, a neuronal-like phenotype in human primary ectomesenchymal dental pulp cells.

Adolescent↗