scholarly journals VIII. On the development of the teeth of the newt, frog, slowworm, and green lizard

1875 ◽  
Vol 165 ◽  
pp. 285-296 ◽  
Keyword(s):  
Enamel Organ ◽  
Human Tooth ◽  
Oral Epithelium ◽  
Sequence Of Events ◽  
Pass Through ◽  
Tooth Germs

The researches of Goodsir, constituting as they did a very material advance in knowledge, became so deeply graven upon the minds of scientific men that subsequent investigations, tending to modify his conclusions in important particulars, have attracted less attention than is their due. As long ago as 1853 Professor Huxley (Quart. Journ. Microscop. Science, vol. i.) published the statement that, in the frog and mackerel at all events, the tooth-germs are at no time in the condition of free papillæ; and in the same paper correctly described the connexion existing between the oral epithelium and the enamel-organ in the fully formed dental sacs. Thus, although Professor Huxley accepted as in most particulars accurate the account given by Goodsir of the sequence of events in the formation of the human tooth-sac, he in some degree anticipated the discovery made by Professor Kölliker some years later (Zeitschrift f. wiss. Zool. 1863), that in several Mammalia the tooth-germs never pass through any papillary stage, but are from the first deep below the surface.

Tissue interactions in embryonic mouse tooth germs

Development ◽  
1970 ◽  
Vol 24 (1) ◽  
pp. 159-171
Author(s):  
Edward J. Kollar ◽  
Grace R. Baird
Keyword(s):  
Enamel Organ ◽  
Oral Epithelium ◽  
Embryonic Mouse ◽  
Tooth Shape ◽  
Structural Specificity ◽  
Dental Papilla ◽  
Tissue Interactions ◽  
Dental Epithelium ◽  
Tooth Germs

The ability of fragments of incisor enamel organ and lip-furrow epithelium from 15- and 16-day old embryonic mice to regulate into harmonious tooth constructions is described. The cervical loop and upper half portions of the incisor enamel organ were confronted with incisor or molar dental papillae. Similar combinations were made from lip-furrow epithelium and incisor or molar papillae. The cultures were grown in the anterior chambers of homologous host eyes. The epithelial fragments from the incisor enamel organ when associated with the dental papillae reconstruct teeth typical in all respects; enamel and dentin matrices are deposited. Lip-furrow epithelium arises from the oral epithelium and is temporally and spatially related to the incisor dental epithelium proper. This ectopic epithelium was confronted by incisor and molar papillae. Harmonious teeth developed in these explants. It is concluded that the ability of the dental papillae to elicit new cytodifferentiative and biochemical syntheses from the lip-furrow epithelium indicates that the dental papillae act inductively during tooth ontogeny. The shape of the teeth reconstructed from enamel organ fragments and lip-furrow epithelium were incisiform or molariform in response to the incisor or molar dental papillae. These data confirm the conclusion that the structural specificity for tooth shape resides in the dental papilla.

scholarly journals Role of Innate Inflammation in the Regulation of Tissue Remodeling during Tooth Eruption

2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Yusuke Makino ◽  
Kaoru Fujikawa ◽  
Miwako Matsuki-Fukushima ◽  
Satoshi Inoue ◽  
Masanori Nakamura
Keyword(s):  
Bacterial Infections ◽  
Tooth Movement ◽  
Tooth Eruption ◽  
Intercellular Adhesion Molecule ◽  
Enamel Organ ◽  
Pcr Analysis ◽  
Maturation Stage ◽  
Oral Epithelium ◽  
Rt Pcr ◽  
Inflammatory Reactions

Tooth eruption is characterized by a coordinated complex cascade of cellular and molecular events that promote tooth movement through the eruptive pathway. During tooth eruption, the stratum intermedium structurally changes to the papillary layer with tooth organ development. We previously reported intercellular adhesion molecule-1 (ICAM-1) expression on the papillary layer, which is the origin of the ICAM-1-positive junctional epithelium. ICAM-1 expression is induced by proinflammatory cytokines, including interleukin-1 and tumor necrosis factor. Inflammatory reactions induce tissue degradation. Therefore, this study aimed to examine whether inflammatory reactions are involved in tooth eruption. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed sequential expression of hypoxia-induced factor-1α, interleukin-1β, and chemotactic factors, including keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2 (MIP-2), during tooth eruption. Consistent with the RT-PCR results, immunohistochemical analysis revealed KC and MIP-2 expression in the papillary layer cells of the enamel organ from the ameloblast maturation stage. Moreover, there was massive macrophage and neutrophil infiltration in the connective tissue between the tooth organ and oral epithelium during tooth eruption. These findings suggest that inflammatory reactions might be involved in the degradation of tissue overlying the tooth organ. Further, these reactions might be induced by hypoxia in the tissue overlying the tooth organ, which results from decreased capillaries in the tissue. Our findings indicate that bacterial infections are not associated with the eruption process. Therefore, tooth eruption might be regulated by innate inflammatory mechanisms.

Immunohistochemical demonstration of bcl-2 protein in human tooth germs

1994 ◽  
Vol 39 (7) ◽  
pp. 545-550 ◽  
Author(s):  
P.J. Slootweg ◽  
R.A. de Weger
Keyword(s):  
Human Tooth ◽  
Immunohistochemical Demonstration ◽  
Tooth Germs

Transplantation of Human Tooth Germs to Lower Animals

1955 ◽  
Vol 34 (3) ◽  
pp. 329-340 ◽  
Author(s):  
Harold S. Fleming
Keyword(s):  
Human Tooth ◽  
Tooth Germs

TheHOX 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

2006 ◽  
Vol 97 (4) ◽  
pp. 836-848 ◽  
Author(s):  
Vincenzo D'Antò ◽  
Monica Cantile ◽  
Maria D'Armiento ◽  
Giulia Schiavo ◽  
Gianrico Spagnuolo ◽  
...  
Keyword(s):  
Neuronal Differentiation ◽  
Dental Pulp ◽  
Human Tooth ◽  
Dental Pulp Cells ◽  
Network Activation ◽  
Pulp Cells ◽  
Tooth Germs

Distribution pattern of cholinesterase enzymes in human tooth germs

2010 ◽  
Vol 55 (8) ◽  
pp. 561-569 ◽  
Author(s):  
T.L. Nandasena ◽  
C.K. Jayawardena ◽  
W.M. Tilakaratne ◽  
C.D. Nanayakkara
Keyword(s):  
Distribution Pattern ◽  
Human Tooth ◽  
Tooth Germs

Localization of Cellular Calcium in Differentiating Ameloblasts and Its Relationship To the Early Mineralization Process in Mantle Dentin and Enamel in Hamster Tooth Germs in Vitro

1987 ◽  
Vol 1 (2) ◽  
pp. 202-212 ◽  
Author(s):  
D.M. Lyaruu ◽  
A.L.J.J. Bronckers ◽  
J.H.M. Woltgens ◽  
K. Hoeben-Schornagel
Keyword(s):  
Plasma Membranes ◽  
Ultrastructural Level ◽  
Enamel Organ ◽  
Mineralization Process ◽  
Calcium Gradient ◽  
Maxillary Molar ◽  
Dentin Mineralization ◽  
Tooth Germs

The relationship between the distribution of calcium in the cells of the enamel organ and the mineralization process in mantle dentin and enamel was investigated at the ultrastructural level in cultured hamster second maxillary molar tooth germs explanted before the onset of mineralization (bell stage). During the early stages of pre-odontoblast and pre-ameloblast differentiation, pyroantimcnate (PA) reaction product for calcium was observed only in the nuclei. However, an abrupt increase in PA reaction product appeared in the apical cytoplasm of both the pre-odontoblasts and pre-ameloblasts prior to the onset of mantle dentin mineralization. In the pre-dentin, the PA reaction product was localized mainly on the striated collagen fibers. The PA reaction product in the apical poles of these cells increased concomitantly with increasing mantle dentin mineralization. The amounts of PA reaction product along the plasma membranes and in the cytoplasm decreased in the direction of the basal (stratum intermedium) pole. The highest PA activity in the cytoplasmic side of the plasma membranes of the ameloblasts was found during the secretory phase of amelogenesis. However, in the area around the tips of the Tomes' processes, membrane-associated and cytoplasmic PA activity was low or absent but gradually increased toward the ameloblast cell body, an indication of the presence of a calcium gradient in the processes. These results indicate that in vitro: (1) both odontoblasts and (pre)-ameloblasts are involved in the calcium acquisition necessary for the initial stages of mantle dentin mineralization; (2) in ameloblasts, there is a calcium gradient in the direction of the mineralization front from the earliest stages of mantle dentin mineralization onward; (3) enamel matrix does not seem to be involved in calcium translocation to the enamel mineralization front; (4) the Tomes' processes seem to regulate transmembrane calcium transport to the mineralization front; and (5) the distribution of calcium in the enamel organ is comparable with that found in vivo.

scholarly journals Micro-PIGE determination of fluorine distribution in developing hamster tooth germs.

1989 ◽  
Vol 37 (5) ◽  
pp. 581-587 ◽  
Author(s):  
D M Lyaruu ◽  
W J Lenglet ◽  
J H Wöltgens ◽  
A L Bronckers
Keyword(s):  
Gamma Ray ◽  
Enamel Organ ◽  
Fluorine Concentration ◽  
X Rays ◽  
Enamel Formation ◽  
Early Maturation ◽  
Maturation Stages ◽  
High Doses ◽  
Tooth Germs

A micro-PIGE (Proton-Induced gamma-ray Emission) technique based on the delayed 5/2+----1/2+ nuclear transition of fluorine (E gamma = 197 keV, t1/2 = 87 ns) emitted after 19F(p,p', gamma)19F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose of sodium fluoride (20 mg NaF/kg body weight). The aforementioned nuclear reaction is unique for fluorine, and therefore detection of gamma-rays emanating from this reaction in a biological specimen implies a positive identification of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mineralization and fluoride incorporation into the enamel organ. The highest fluorine concentration in the enamel organ was recorded in the dentin near the dentin-enamel junction (DEJ). In the enamel, the highest concentration of fluorine was found to be associated with the more mature areas of the enamel near the DEJ, but gradually decreased in the direction of the enamel surface. Fluorine was not detected in the control germs. These results suggest that administration of fluoride in high doses during the pre-eruptive stages of enamel formation leads to incorporation of the ion into the forming dentin and enamel mineral, and that the enamel matrix does not seem to bind fluoride avidly.

Bivalent Histone Codes on WNT5A during Odontogenic Differentiation

2017 ◽  
Vol 97 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Y. Zhou ◽  
L. Zheng ◽  
F. Li ◽  
M. Wan ◽  
Y. Fan ◽  
...  
Keyword(s):  
Tooth Development ◽  
Mesenchymal Cell ◽  
Human Tooth ◽  
Dependent Manner ◽  
Promoter Regions ◽  
Odontogenic Differentiation ◽  
Tooth Germs ◽  
Histone Codes ◽  
Lineage Specific Genes ◽  
Coactivator Complex

Lineage-committed differentiation is an essential biological program during odontogenesis, which is tightly regulated by lineage-specific genes. Some of these genes are modified by colocalization of H3K4me3 and H3K27me3 marks at promoter regions in progenitors. These modifications, named “bivalent domains,” maintain genes in a poised state and then resolve for later activation or repression during differentiation. Wnt5a has been reported to promote odontogenic differentiation in dental mesenchyme. However, relatively little is known about the epigenetic modulations on Wnt5a activation during tooth development. Here, we investigated the spatiotemporal patterns of H3K4me3 and H3K27me3 marks in developing mouse molars. Associated H3K4me3 methylases (mixed-lineage leukemia [MLL] complex) and H3K27me3 demethylases (JMJD3 and UTX) were dynamically expressed between early and late bell stage of human tooth germs and in cultured human dental papilla cells (hDPCs) during odontogenic induction. Poised WNT5A gene was marked by bivalent domains containing repressive marks (H3K27me3) and active marks (H3K4me3) on promoters. The bivalent domains tended to resolve during inducted differentiation, with removal of the H3K27me3 mark in a JMJD3-dependent manner. When JMJD3 was knocked down in cultured hDPCs, odontogenic differentiation was suppressed. The depletion of JMJD3 epigenetically repressed WNT5A activation by increased H3K27me3 marks. In addition, JMJD3 could physically interact with ASH2L, a component of the MLL complex, to form a coactivator complex, cooperatively modulating H3K4me3 marks on WNT5A promoters. Overall, our study reveals that transcription activities of WNT5A were epigenetically regulated by the negotiated balance between H3K27me3 and H3K4me3 marks and tightly mediated by JMJD3 and MLL coactivator complex, ultimately modulating odontogenic commitment during dental mesenchymal cell differentiation.

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