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PubMed2001

Epigenetic signals during odontoblast differentiation.

Odontoblast terminal differentiation occurs according to a tooth-specific pattern and implies both temporospatially regulated epigenetic signaling and the expression of specific competence. Differentiation of odontoblasts (withdrawal from the cell cycle, cytological polarization, and secretion of predentin/dentin) is controlled by the inner dental epithelium, and the basement membrane (BM) plays a major role both as a substrate and as a reservoir of paracrine molecules. Cytological differentiation implies changes in the organization of the cytoskeleton and is controlled by cytoskeleton-plasma membrane-extracellular matrix interactions. Fibronectin is re-distributed during odontoblast polarization and interacts with cell-surface molecules. A non-integrin 165-kDa fibronectin-binding protein, transiently expressed by odontoblasts, is involved in microfilament reorganization. Growth factors (TGF beta 1, 2, 3/BMP2, 4, and 6), expressed in tooth germs, signal differentiation. Systemically derived molecules (IGF1) may also intervene. IGF1 stimulates cytological but not functional differentiation of odontoblasts: The two events can thus be separated. Immobilized TGF beta 1 (combined with heparin) induced odontoblast differentiation. Only immobilized TGF beta 1 and 3 or a combination of FGF1 and TGF beta 1 stimulated the differentiation of functional odontoblasts over extended areas and allowed for maintenance of gradients of differentiation. Presentation of active molecules in vitro appeared to be of major importance; the BM should fulfill this role in vivo by immobilizing and spatially presenting TGF beta s. Attempts are being made to investigate the mechanisms which spatially control the initiation of odontoblast differentiation and those which regulate its propagation. Analysis of molar development suggested that odontoblast differentiation and crown morphogenesis are interdependent, although the possibility of co-regulation requires further investigation.

Adhesins, Bacterial↗
PubMed2005

[Culture and phenotype characteristics of mouse dental follicle cells].

OBJECTIVE: To establish a method for isolating and culturing mouse dental follicle cells and to study the phenotype characteristics of dental follicle cells. METHODS: Mandibular first molars from 9 day old Balb/c mice were digested with 1% trypsin, subsequently, and the dental follicle was enucleated from the tooth germ and cultured. The shape and ultrastructural appearance of dental follicle cells were observed under phase-contrast microscope and scanning electron microscope (SEM). Immunocytochemistry was used to detect the expression of alkaline phosphatase (ALP), bone sialoprotein (BSP) and osteopontin (OPN). RESULTS: Three types of cells were isolated: some were cuboidal/polygonal; some were elongated, spindle-shaped, fibroblast-like cells; and a minor, third cell type was very thin and elongated. The cytoplasm of the first two cell types was filled with abundant granules. The cells were pleomorphism under SEM and had many filipodia and microvilli. According to whether there were filaments overlying the surface, the cells could be divided into two subtypes. Some but not all follicle cells expressed ALP, BSP and OPN. CONCLUSION: The cultured dental follicle cells consisted of several cell phenotypes and had the potential of differentiating into cementoblasts, periodontal ligament fibroblasts and osteoblasts.

Alkaline Phosphatase↗
PubMed1997

Evidence for a local action of growth hormone in embryonic tooth development in the rat.

Studies in non-dental embryonic tissues have suggested that an interaction between growth hormone and its receptor may play a role in growth and development before the foetal pituitary gland is competent. This study reports the distribution of growth hormone, its receptor and binding protein in developing rat tooth germs from embryonic day 17 to 21 and postnatal day 0 using antibodies specific for each of these proteins. Four foetal rats were processed at each time point (E17, E18, E20/21 and postnatal day 0). Following routine fixation and paraffin embedding, sections were treated with antisera to rat growth hormone, rat growth hormone binding protein and growth hormone receptor. Localization of antibody/antigen complexes was subsequently visualized by addition of biotinylated IgG and reaction with streptavidin peroxidase and diaminobenzidine. Assessment of the level of staining was qualitative and based on a subjective rankings ranging from equivocal to very strong staining. Overall, growth hormone and its binding protein were located both in the cellular elements and throughout the extracellular matrix, whereas the growth hormone receptor showed an exclusively intra-cellular location. All three proteins were detectable in cells of the dental epithelium and mesenchyme at the primordial bud stage (E17) which occurs prior to expression of pituitary growth hormone. At the cap stage of odontogenesis (E18-19), numerous cells in both the dental epithelium and mesenchyme were intensely immunoreactive for growth hormone, its binding protein and receptor. In the succeeding early bell stage (E20-21), most of the mesenchymal cells in the dental pulp were mildly positive for these proteins, while the dental epithelium and adjacent mesenchyme were more immunoreactive. At the late bell stage (postnatal day 0), all three proteins were localized in dental epithelium, differentiating mesenchymal cells the cuspal surface facing the epithelial-mesenchymal interface, preodontoblasts, and odontoblasts forming dentine. From these observations, immunoreactive growth hormone, its receptor and binding protein appear to be expressed in odontogenic cells undergoing histodifferentiation, morphodifferentiation and dentinogenesis in a cell-type and stage-specific pattern throughout embryonic tooth development. This suggests the possibility that growth hormone, or a growth hormone-like protein, plays a paracrine/autocrine role in tooth development in utero.

Animals↗
PubMed2003

Cost, operation and hospitalization times in distraction osteogenesis versus sagittal split osteotomy.

INTRODUCTION: Distraction osteogenesis in 'common' surgical orthodontics is mentioned as an alternative for conventional sagittal split osteotomy. After a 'learning curve' in the surgical skills of distraction, the two techniques can be compared concerning time and cost aspects. PATIENTS: Forty-seven patients (male n=28, female n=19, age 11.7-17.9 yr (mean 14.2) with an Angle's class II division 1malocclusion of skeletal mandibular origin were operated on using distraction osteogenesis and were compared with a second group of 21 patients (male n=4, female n=17, age 16-36yr (mean 22.8) who underwent bilateral sagittal split osteotomies in the same period in order to correct the same type of dysgnathia. METHOD: The first group of 47 patients was treated with intraorally placed bone-born distraction devices to correct mandibular deficiency following a standard protocol, with removal of the third molar tooth germs if present. The second group of 21 patients underwent standard sagittal split osteotomies to correct the mandibular deficiency. The costs of hospitalization, distraction devices and operation time were compared. RESULTS: In this study, distraction osteogenesis took on average more operative time (mean 37%), but 1 day less hospitalization than the bilateral sagittal split osteotomies. The surgical cost of distraction osteogenesis was 36% higher than the conventional sagittal split osteotomy. CONCLUSION: In this study, correcting Angle's class II deficiencies by means of distraction osteogenesis was shown not to be a time-saving procedure when compared with sagittal split osteotomy. Surgical costs were significantly higher using distraction, mainly due to the price of the distractors. Changes in hospital policies concerning hospital admission of adults and children and European legislation concerning re-usability of surgical instruments may balance the cost of both procedures.

Adolescent↗
PubMed1985

Ultrastructural distribution of acidic glycosaminoglycans associated with matrix vesicle-mediated calcification in mouse progenitor predentine.

The ultrastructural localization of acidic glycosaminoglycans, presumed to be proteoglycans, was examined during initial matrix vesicle-mediated calcification in dentine, by using ruthenium red (RR) staining, high iron diamine thiocarbohydrazide silver proteinate (HID-TCH-SP) staining, and an enzymatic digestion method. Progenitor predentine 2-10 micron width of developing mouse molar tooth germs was used throughout the present study. The outer surface membrane of the intact matrix vesicles had a strong affinity for RR. The RR positive materials appeared beaded and extended perpendicularly from the vesicle membrane. They tended to disappear with the disruption of the vesicular membrane, which resulted from overextension due to needle-like, crystal-like structures. The HID-TCH-SP stain deposits, approximately 10 nm in diameter, were densely distributed around the intact matrix vesicles, though few were found inside them. Some matrix vesicles that were presumably disrupted, however, contained smaller stain deposits. On the outer surface membrane of the disrupted vesicles, HID-TCH-SP stain deposits were fewer in number. The results obtained from enzymatic degradation studies showed that the anionic materials on the outer surface membrane of the matrix vesicles were represented by chondroitin-4-sulfate and/or chondroitin-6-sulfate. We suggest that chondroitin sulfates attached to the outer leaflet of the vesicular membrane play an important role during the incipient stage of the matrix vesicle-mediated calcification process.

Animals↗
PubMed2006

Fluoride alters type I collagen expression in the early stages of odontogenesis.

Fluoride alters the expression and post-translational modifications of extracellular matrix proteins in dentin. The aim of our study was to determine the effects of fluoride on type I collagen expression during the early stages of tooth germ development in rats. Pregnant dams were divided into three groups and fed a standard diet. From the fifth day of pregnancy the three groups received tap water with, respectively, trace amounts of fluoride (C), a low fluoride concentration (FL) or and a high fluoride concentration (FH). Changes in type I collagen expression and distribution were evaluated. The expression of type I collagen was restricted to the extracellular spaces of cells of mesenchymal origin. In the youngest animals the most intense immunoreactivity for type I collagen was detected in predentin of the FL group. Although the intensity of immunostaining increased in proportion to the age of the animals, the largest increase in the groups investigated was detected in the FL group. We concluded that a low concentration of fluoride can act as a stimulator of type I collagen deposition in the extracellular matrix of dentin, while high concentrations of fluoride have an opposite effect, acting as an inhibitor of type I collagen formation in dentin.

Animals↗
PubMed1992

Immunofluorescent lectin binding patterns and glycoprotein co-localization in the developing murine molar tooth.

Fluorescein-conjugated lectins were used in conjunction with antibodies to laminin, tenascin and amelogenin to investigate saccharide expression in the developing tooth germ. At the bud stage, peanut agglutinin (PNA) binding demonstrated residues that may be D-galactose-(beta 1----3)DGalNAc, and this staining occurred after the expression of tenascin. Only the cap-stage enamel organ suprabasal cells and the enamel knot stained intensely with Ulex europeus agglutinin-I, but not Lotus tetragonolobus agglutinin, implying the transient presence of blood group H type I oligosaccharides. At the late stages of amelogenesis, enamel synthesis is preceded by en bloc loss of inner enamel basement membrane components. Before this, Bandeiraea (Griffonia) simplicifolia--I (BSL-I) staining was lost from postmitotic ameloblasts, suggesting that a glycosylated species is initially removed. Additionally, PNA was co-localized with amelogenin protein, suggesting that it may express beta-D-galactosyl sequences. These results indicate that the glycosylation patterns of matrix components during odontogenesis may be important as they vary in a manner similar to that of the well-known glycoproteins.

Acetylgalactosamine↗
PubMed1985

Freeze-fracture replicas of rat ameloblasts reveal unusual membrane domains around gap junctions.

Specimens of aldehyde-fixed and glycerol-impregnated tooth germs obtained from 1-2 day old rats were prepared for ultrathin section studies and for freeze-fracture, with the purpose of studying the structural organization of membranes of developing ameloblasts. In this report we describe unusual membrane domains which were found surrounding several ameloblast gap junctions. Developing ameloblasts - when examined in ultrathin sections - exhibit gap junctions which appear straight, curved or invaginated. In freeze-fracture replicas, in addition to their typical appearance, several gap junctions were found to be surrounded by a membrane margin which was undulating and devoid of intramembrane particles (IMP's). We believe that these hitherto unreported particle-free membrane margins are associated with the formation of curved or invaginated gap junctions. It is possible that these membrane margins are particle-free because plasma membrane proteins (presumably IMP's) become transiently detached from the cytoskeleton and move laterally. It is therefore likely that these margins are pure lipid domains which are more flexible, thus providing a transient hinge-like mechanism which facilitates the movement required for the formation of the curved or invaginated ameloblast gap junctions.

Ameloblasts↗
PubMed1998

Freeze-fracture studies of the distal plasma membrane of rat odontoblasts during their differentiation and polarisation.

We have examined freeze-fracture replicas of maxillary first molar tooth germs of newborn rats at early stages of dentinogenesis to study the development of tight junctions in the distal plasma membrane of differentiating odontoblasts. In addition, freeze-fracture was combined with filipin to observe the distribution of cholesterol on the distal plasma membrane of odontoblasts during differentiation. Only gap junctions were present in early differentiating odontoblasts. The distal plasma membrane exhibited low cholesterol content, which might indicate high fluidity. With the beginning of mineral deposition in matrix-vesicles, the first signs of tight junction formation were observed. Further development revealed increasingly complex focal tight junctions. In later stages, when mineralisation is observed progressing to the fibrillar and non-fibrillar constituents of the matrix, well developed focal tight junctions were detected. Concomitantly, cholesterol in distal portions of the odontoblast plasma membrane increased, indicating, probably, a higher rigidity. Thus, a distal plasma membrane domain is established, odontoblasts become fully differentiated, and partial compartmentalisation of matrix occurs. At this stage, odontoblasts may be able to secrete specific matrix molecules to ensure the progression of mineralisation.

Animals↗
PubMed1991

Light microscopic, cytochemical and ultrastructural studies of a rat odontogenic epithelial cell line.

An odontogenic epithelial cell line, ROE-2B, was established by propagating disaggregated immature, unmineralized maxillary third molar tooth germs from 11-day old Sprague-Dawley rats on a feeder layer of Mitomycin-C treated NIH 3T3 embryonic mouse fibroblasts. The cell line has been maintained for more than 6 months and through 7 passages. Light microscopic examination of cells revealed colonies with epithelial morphology. Electron microscopic examination confirmed the epithelial nature by the demonstration of tonofilaments, desmosomes and basal lamina. Cells were also shown to have secretory vacuoles, an abundance of granular endoplasmic reticulum, free ribosomes, Golgi complex and mitochondria. Surface activity in the form of pseudopodia-like projections and micropinocytosis were noted. Epithelial cells forming keratin were demonstrated by a positive histochemical reaction with Rhodanile Blue. Immunohistochemical studies showed a positive reaction for CAM 5.2 indicating that the ROE-2B cells express the cytokeratins of simple or glandular epithelia. The ROE-2B cell line will be useful for studies on in vitro biological behaviour of odontogenic epithelial cells, and may allow the establishment of in vitro models of odontogenic tumours.

Animals↗
PubMed2004

Characterization of dental epithelial progenitor cells derived from cervical-loop epithelium in a rat lower incisor.

Dental epithelial progenitor cells differentiate into various cell types during development of tooth germs. To study this mechanism, we produced immortalized dental epithelial progenitor cells derived from the cervical-loop epithelium of a rat lower incisor. The expression patterns of cytokeratin 14, nerve growth factor receptor p75, amelogenin, Notch2, and alkaline phosphatase were examined by immunohistochemistry in both lower and higher cell densities. The patterns of each were compared in the dental epithelium of rat lower incisors. The results demonstrated that these cells could produce ameloblast lineage cells, stratum intermedium cells, stellate reticulum, and outer enamel epithelium. Furthermore, fibroblast growth factor 10 stimulated proliferation of dental progenitor cells and subsequently increased the number of cells expressing alkaline phosphatase. These results suggest that fibroblast growth factor 10 plays a role in coupling mitogenesis of the cervical-loop cells and the production of stratum intermedium cells in rat incisors.

Alkaline Phosphatase↗
PubMed1987

Transferrin and tooth morphogenesis: retention of transferrin by mouse embryonic teeth in organ culture.

Transferrin is the only serum protein that is required for the early morphogenesis of mouse embryonic teeth in organ culture. Transferrin is able to support tooth morphogenesis and dental cell differentiation by stimulating cell proliferation. Its role in this process is restricted exclusively to iron transport, which takes place by receptor-mediated endocytosis of iron-loaded transferrin. A lipophilic iron chelator, pyridoxal isonicotinoyl hydrazone (PIH), can replace transferrin and support tooth morphogenesis in organ culture. We studied the effects of these two iron transporters on cell proliferation in tooth germs during culture. We found that Fe-PIH and transferrin stimulate proliferation to a similar extent in early cap-stage teeth of 14-day mouse embryos, but have no effect on cell proliferation in bell-stage teeth of 16-day mouse embryos. Day-16 teeth undergo morphogenesis in unsupplemented chemically defined medium, whereas transferrin or Fe-PIH is needed for the morphogenesis of day-14 teeth. Although the need for exogenous iron-transport molecules is lost with advancing development, the level of mitotic activity is still fairly high in bell-stage teeth. The abundant binding of transferrin in areas of active cell proliferation in bell-stage teeth also suggests that transferrin is still needed and used for the transport of iron into proliferating cells. Transferrin is not degraded by the process of receptor-mediated endocytosis. After releasing iron into a cell, transferrin is returned to the extracellular space and is reused. We therefore studied whether the transferrin needed by bell-stage teeth could be adequately supplied by endogenous transferrin synthesized or stored in tissue explants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Presence of alpha-naphthyl acetate esterase enzymes in dental and oral epithelium of guinea pig embryos.

This study examines the distribution of alpha-naphthyl acetate esterase enzymes in reduced enamel epithelium, i.e., post secretory ameloblasts (PSA) and external cells of reduced enamel epithelium (ERE) of continuously growing incisor and molar tooth germs and in the covering oral epithelium (OE). Jaws of guinea pig embryos, 25-50 days of gestation age, were pretreated, frozen, serially cut, and incubated with alpha-naphthyl acetate as substrate and hexazotized pararosaniline as capture agent for demonstration of enzyme activity. In addition, sections were preincubated with various inhibitors of enzyme activity. A strong enzyme reaction, essentially unaffected by pretreatment procedures, was demonstrated in all cells of PSA and ERE, and in suprabasal cells of OE. Preliminary characterization of the alpha-naphthyl acetate esterase enzymes by means of inhibitors suggests a prevailing presence of B-esterase enzymes in both oral and dental epithelia. PSA were selectively stained when 2 x 10(-3) M arsanilic acid was used as inhibitor, ERE were selectively inhibited by 10(-5) M eserine, and cells of OE were selectively stained when 2 x 10(-3) M HgCl2 was used as inhibitor. We therefore conclude that the alpha-naphthyl acetate esterase enzymes in combination with inhibitors may serve as histochemical markers for discrimination of dental and oral epithelium in the guinea pig prior to eruption of teeth.

Ameloblasts↗
PubMed1992

Proliferative and functional stages of rat ameloblast differentiation as revealed by combined immunocytochemistry against enamel matrix proteins and bromodeoxyuridine.

A double-staining immunocytochemical technique was used for the simultaneous detection, at the light- and electron-microscopical level, of proliferating bromodeoxyuridine (BrdU)-labelled cells and enamel protein (EP)-producing cells in the inner enamel epithelium (IEE) of rat tooth germ. BrdU-positive cells were found in the region of the IEE close to the cervical loop and never displayed EP-like immunoreactivity. BrdU-immunoreactivity was confined to the nucleus of replicating cells. In contrast, epithelial cells displaying EP-like immunoreactivity were found in the region of the forming dental cusp and were consistently BrdU-negative. EP-like immunoreactivity was detectable in the cytoplasmic compartments involved in the exocrine secretion pathway and in the extra-cellular matrix close to EP-immunoreactive cells. These data support the view that withdrawal from the cell cycle in the IEE is a temporal prerequisite for acquiring the functional competence of secreting EP. Moreover, cycling cells and secretory cells in the IEE constitute two separate compartments that are spatially defined, and that exhibit clear-cut staining patterns with respect to BrdU- and EP-immunoreactivity, respectively. We thus propose that BrdU-incorporation and EP-production may be used as specific markers of the differentiation of the IIE cells in studies of the possible role of growth factors, their receptors and oncoproteins in this tissue.

Ameloblasts↗
PubMed1998

Laminin gamma2 expression is developmentally regulated during murine tooth morphogenesis and is intense in ameloblasts.

Mutations in the laminin gamma2 gene cause junctional epidermolysis bullosa, and enamel hypoplasias are frequently seen in these patients. Laminin gamma2 is one of the three polypeptide chains forming the basement membrane glycoprotein laminin-5. We have localized the expression of the laminin gamma2 gene by in situ hybridization during mouse tooth development from early morphogenesis to completion of crown development. The expression was restricted to epithelial cells. During the early morphogenesis of the tooth germ, laminin gamma2 was expressed by the outer dental epithelium and by the stellate reticulum cells. No expression was detected in the cells of the inner dental epithelium giving rise to ameloblasts. The pre-ameloblasts remained negative during the early bell stage, but, interestingly, expression was very prominently upregulated as the cells differentiated into ameloblasts. This upregulation appeared to coincide with the start of enamel matrix secretion. The ameloblasts expressed laminin gamma2 intensely throughout the period of active enamel deposition. The expression continued at a lower level in the maturation-stage ameloblasts covering the enamel surface. Immunolocalization of laminin-5 with polyclonal antibodies indicated that the protein formed a continuous lining at the basal surfaces of the cells expressing the laminin gamma2 transcripts. We suggest that the role of laminin-5 during enamel formation may be to strengthen the anchorage of the ameloblasts to the enamel matrix, and that the pathogenesis of enamel hypoplasias in cases of laminin-5 mutations could be associated with detachment of the ameloblast cell layer from the enamel surface.

Ameloblasts↗
PubMed1999

Temporal and spatial expression of c-jun and jun-B proto-oncogenes in pulp cells involved with reparative dentinogenesis after cavity preparation of rat molars.

c-jun and jun-B are nuclear proto-oncogenes induced by growth factors such as bone morphogenetic proteins (BMPs). These gene products enhance the expression of many genes, including osteocalcin and collagen types, indicating that c-jun and jun-B play important roles in the cell differentiation process. It is also known that BMPs affect the differentiation of pulp cells to odontoblast-like cells during reparative dentinogenesis, but little is known about the transcriptional regulation of genes in cells associated with reparative dentinogenesis. In this study, we examined the expression of c-jun and jun-B in pulp cells during reparative dentinogenesis after cavity preparation of rat molars by in situ hybridization. In rat tooth germs, c-jun and jun-B were co-expressed in the odontoblastic lineage. In rat adult molars, c-jun was expressed in the odontoblast layer, but the jun-B expression was absent in all pulp cells. After cavity preparation, we found that c-jun and jun-B were coexpressed in pulp cells underneath cavities. During the early phase of reparative dentinogenesis, levels of c-jun and jun-B greatly increased in pulp cells within and around the reparative dentin matrix formed adjacent to the cavity floor. Fourteen days after cavity preparation, c-jun and jun-B were expressed only in pulp cells lining the irregular surface of the thick reparative dentin. These results suggest that c-jun and jun-B may play important roles both in physiological and in reparative dentinogenesis; in particular, the limited distribution of the jun-B expression suggests a specific role of jun-B only in cells involved with the active formation of the dentin matrix during primary and reparative dentinogenesis.

Animals↗
PubMed2000

Specialized basement membrane of monkey maturation stage ameloblasts mediates firm ameloblast-enamel association by its partial calcification.

A basement membrane-like structure associated with the maturation stage ameloblasts of the monkey (Macaca fuscata) tooth germ was examined with high resolution electron microscopy. The tissue was prepared either with or without demineralization. This structure was composed of a lamina lucida-like (lamina lucida) and lamina densa-like (lamina densa) structure. The latter was made up of a fine "cord" network, the major constituent of the basement membrane. It was closely associated with the third layer of a 200 nm wide looser cord network. In specimens without demineralization the third layer and a part of the lamina densa were calcified, and it formed the edge of the enamel. This particular area had a higher electron density, and the size, shape, and arrangement of mineral crystals were different from those of the rest of the enamel. Also, mineralization appeared to be proceeding along the cords. These observations indicate that this dense layer is a highly specialized basement membrane which mediates the firm association of maturation stage ameloblasts with the enamel by means of the mineralization of a part of this basement membrane itself which becomes integrated as a part of the enamel. Also, this highly specialized manner of association is favorable with the reported control of the loss of organic substances in the maturing enamel by maturation stage ameloblasts.

Ameloblasts↗
PubMed1990

Calcification capacity of dental papilla mesenchymal cells transplanted in the isogenic mouse spleen.

The capacity of the dental pulp to form calcified tissue was examined in papilla cells dissociated from first molar tooth germs of the neonatal mouse and isografted in the spleen for up to 7 days. To obtain papilla cell populations without odontoblasts, pulpal mesenchyme was isolated mechanically from the enamel organ after 0.1% trypsin treatment and rolled on a membrane filter. On day 3 after transplantation, the grafted papilla cells had changed into large, spindle-shaped cells, and initial calcification with needle-like crystals began in association with the collagenous matrix surrounding those cells. On day 7 after transplantation, the spindle cells transformed into odontoblast-like cells containing well-developed secretory organelles, and irregular, but nontubular, calcified tissues were commonly observed surrounding the extracellular collagenous matrix. The calcified tissue matrix with cellular inclusions displayed a structure similar to that of osteodentin. During this period, an intense positive reaction for alkaline phosphatase (ALPase) activity was demonstrated along the cell membranes of the odontoblast-like cells aligned at the periphery of forming calcified tissue. Enzymatic activity could not be detected on the cells incorporated completely into osteodentin-like matrix. The present results show that the papilla cell population transplanted into the spleen formed osteodentin-like material, thus demonstrating the capacity of papilla cells to produce calcified tissue.

Alkaline Phosphatase↗