El objetivo de este articulo es hacer una revisión bibliográfica .. en la formación del esmalte y la dentina durante la odontogenesis, como las. During odontogenesis from this stylar shelf different morphological dental traits emerge, such as cuspal talon and lobes which form the cingulum itself in anterior . odontogénesis, pueden ser eumórfico o dismórfico, único o múl- tiple, erupcionado liza una revisión bibliográfica de diferentes artículos y textos en diferentes.
|Country:||Sao Tome and Principe|
|Published (Last):||20 November 2011|
|PDF File Size:||11.99 Mb|
|ePub File Size:||8.18 Mb|
|Price:||Free* [*Free Regsitration Required]|
Many of Glycobyological aspects of human development remain still unclear, mainly in oral science, and this could be observed in a lack of literature with few and old papers about this subject.
During tooth histo-morphogenesis changes occur in basement membrane composition, expression of signaling molecules and in localization odontogeenesis cell surface components, where glyco components could be involved. In this sense, this work aimed to analyze the ConA ligands commonly founded in glycoproteins cores and UEA-I ligands since fucolization is a Key event in many physiological and pathological processes.
Therefore 15 jaws of human fetuses were ethically obtained, histologicaly processed and then submitted to lectin histochemistry with appropriated controls.
The tick tock of odontogenesis.
Interestingly, Con A ligands were not founded in the basement membrane of the stratum intermedium of the enamel differing from rodents models. The staining pattern of UEA-I was different, starting to be positive in the ectomesenchyma since the bud stage and shown variable expression in cell type and staining intensity, which appeared be directly proportional to the progress of odontogenesis. Thus, this work shows that Con A and UEA-I exhibit odonhogenesis growing staining directly proporcional to ameloblasts and odontoblasts cytodiferenciation and revels idontogenesis glycan differences between human odontogenesis and rodents models.
Odontogenesis; Carbohydrates; Lectin histochemistry. Curiosamente, ligandos de la ConA no se encontraron en la membrana basal de la capa intermedia del esmalte, difiriendo de los modelos de roedores. Tooth odontogemesis involves morphogenesis, epithelial histogenesis and cell differentiation.
The consecutive morphological oddontogenesis of lamina, bud, cap and bell are also characterized by changes in epithelial histogenesis. Differential cell proliferation rates, apoptosis, and alterations in adhesion and cell shape lead to the positioning of groups of cells with different functions. Many transcription factors, growth factors and growth factor receptors have been found aryiculos dental development and are involved in epithelial-mesenchymal interaction Hikake et al. Given their ubiquitous presence and varied complexity on all cell surfaces, glycans have many diverse roles in development and various physiological systems of complex multicellular organisms Varki et al.
Only little information is available about glycobiology events of oral development in addiction to this there is a lack in literature with few and old papers about this subject. The good news is that many aspects of these glycans could be deciphered by lectins. Lectins are structurally diverse carbohydrate-binding proteins or glycoproteins that agglutinate cells and recognize carbohydrates in oligosaccharides and glycoconjugates Gemeiner et al.
By virtue of their binding specifities, lectins have been used in histochemistry, providing a sensitive detection system for changes in glycosylation and carbohydrate odontigenesis that that may occur during embryogenesis, growth and disease Campos et al.
Tumour lectinology has so far shown cytochemical and histochemical differences between normal and transformed oral tissues including in a single class of tumour Sobral et al. In this sense this work aimed to evaluate Con A and UEA-I ligands spatially and temporally during different phases of human odontogenis comparing with data of rodent models. Slices were treated with 0.
PBS 10 mM phosphate buffer, pH 7. Peroxidase was visualized with a solution of diaminobenzidine-H2O2 for min than counter-staining in Hematoxylin and evaluated by light microscopy. Lectin-binding inhibition assays were developed by incubating lectin with its corresponding specific sugars, methyl-a-D-mannoside for Con A and L-fucose for UEA-I mM prior to sample incubation and replacing the lectin for PBS too.
Cases of Mucoepidermoide carcinoma were used as positive controls and all experiments were done on triplicate. The deciduous tooth germs were founded from the final button stag in the 14th week of fetus development until the start of the crown formation from the 24th week of developmentwith the earlier development in the anterior portion of the jaw. The tooth buds in the early stages of crown formation exhibited the beginning of matrix secretion of the mantle dentin and enamel.
But this patterns of staining changed substantially during 23rd week of intrauterine development. Con A positivity started to be observed in dental papilla with staining intensity ranged from poor to moderate increasing as the cells became closer of the dental epithelium Figs.
This structure showed intensely stained on the papilla periphery too Figs. In the tooth germ at the crown stage Con A was positive at the limit between pre- dentin and ameloblasts, in a weakly pattern and on dentin and enamel matrix Figs. A ConA staining on inner epithelium of enamel organ x and b x. C On the crow phase ConA ligands are expressed on enamel matrix x and d x. E Ameloblast cytoplasma are recognized by the lectin arrows.
This lectin showed a variable expression in cell type and intensity of staining, which appeared be directly proportional to the progress of odontogenesis. The tooth buds 15 weeks of developmentduring the bell phase, showed weak positive staining on ectomesenchymal cells. Meanwhile in 16th weeks of intrauterine development these same cells revealed strong staining on ectomesenchyme and its limit with epithelium, indeed, the epithelial cells of the enamel were moderately stained Fig.
In bell phase 18 weeks were observed weak cytoplasmic staining on ectomesenchymal cells of the follicle, dental papilla Fig. With 23 weeks of intrauterine development the germ showed papilla and follicle ectomesenchymal cells moderately stained, differing from odontoblasts which exhibited intense staining pattern, mainly in areas corresponding to the vertices of future cusps.
The Tick Tock of Odontogenesis
The epithelial cells near the inner and outer epithelium were positive, however, the central portion of the stellate reticulum showed no expression for the UEA-I ligands Fig.
On the 25thweeks, at the crown stage dental germs present dental papilla, odontoblasts, ameloblatos matrix of enamel and dentin intensely stained. This finding was also observed in fetuses between 26 and 28 weeks age of gestational data not shown. C On bell phase, ectomesenchymal cells write arrow were stained as its limit with epithelium, indeed, the epithelial cells of the enamel were moderately stained black arrow x. Many molecular processes involved in odontogenesis are still poorly understood mainly glycobiologic ones.
Gene knockout experiments in mice have demonstrated a critical role in embryogenesis for all major classes of glycans, as well as for certain classes of monosaccharides Varki odontogenesls al. As might be expected, the resulting embryonic phenotypes are complex, and no single mechanism can easily explain the causes of lethality. The gol of this work was to evaluate spatial and temporal changes of UEA-I and ConA ligands during tooth human development to validate animal models more representative of human molecular profiles.
According Campos et al. On odontogenesis the changes of carbohydrates expression may act as modulators of the dental germs formation process, they can odojtogenesis pivotal functions like ligation pattern of growth factors, as well as the movements of migration and recognition that are involved in tooth formation Fuenzalida et al. Some authors have highlighted the role of cell surface proteoglycans sindecan-1 and matrix glycoproteins tenascin as active participants of inductive mechanisms Hikake et odontogenesos.
The expression of Con A ligands are shown in the cells of the enamel and dental papilla of the teeth that were in bell and crown phases. However, Kobayashi et al. Other divergent results about animal models of dental development has been observed on literature for example: These models articuos are founded in other odontogendsis and organs like isoflavonas metabolism in mammalian cells Bursztyka et al. We founded that in the crown stage Con A ligands pattern was positive at the boundary between pre- dentin and ameloblasts staining weakly dentin matrix and enamel, while the staining in the apical portion of the ameloblasts was intense, as in the apical cytoplasm of odontoblasts.
The aritculos occurs when the pre-odontoblasts and pre-ameloblasts differentiate into cells secreting dentin matrix enamel, respectively Nakai et al. Ameloblasts and odontoblasts in fetuses from 23th week, showed intense Con A staining, especially in structures that correspond to the vertices of future cusps.
The temporal expression in all phases of dentinogenesis and different spatial expression mainly observed in the membrane odontogeneesis founded of UEA-I ligands are in agreement with literature results Nakai et al.
Our articulod suggest that L-fucose expression in dentinogenesis is similar between human and rodents models and we hipotyze that this monosaccharide was intensily required on dentinogenesis. For example, disruption of protein O-fucosylation causes a defect in Notch receptors that results in a severe embryonic phenotype Stanley, Ectomesenchymal Condensation behind the tooth germ has show positivite with temporal increment staining for booth lectins but there is a spatial diference.
Articulso UEA is positive since button phase ConA only recognize its ligands from the crown stage, when odohtogenesis papilla and dental follicle were alredy.
This lectins can be used in dental germs for determining the onset secretion of mineral matrix, since the expression of glucose and fucose only will be positive when differentiation of precursor cells in secretory odontoblasts and ameloblasts occurs.
Light-microscopic odontogeneiss on spatial and temporal binding of the lectins concanavalin A, wheat-germ agglutinin and peanut odontognesis in early rat odontogenesis. Comparison of genistein metabolism in rats and humans using liver microsomes and hepatocytes. Acridinium ester conjugated to lectin as chemiluminescent histochemistry marker.
Lectin binding patterns of odontogenic epithelium in the rat during various phases of molar tooth development. Histochemical detection of sugar residues in lizard teeth Liolaemus gravenhorsti: Role of Glycosylation in Development. Berl5: Immunofluorescent lectin binding patterns and glycoprotein co-localization in the developing murine molar tooth. Lectin-binding sites in the growing end of rat incisors.
Shika Kiso Igakkai Zasshi, 31 1: Bone morphogenetic proteins in the early development of zebrafish. Detection of sugar residues in rabbit embryo teeth with lectin-horseradish peroxidase conjugate: A light microscopal study. Epithelial histogenesis during tooth development.
The Tick Tock of Odontogenesis
Lectin-binding patterns in the developing tooth. Lectin cytochemistry on the stratum intermedium and the papillary layer in the rat incisor enamel organ. Regulation of Notch signaling by glycosylation. Glycans odontkgenesis development and Systemic Physiology. New York, Cold Spring Harbor, RESULTS The deciduous tooth germs were founded from the final button stag in the 14th week of fetus development until the start of the crown formation from the 24th week of developmentwith the earlier development in the anterior portion of the jaw.
Casilla D Temuco – Chile Tel.: