ABSTRACT
El presente trabajo se realizó con el objeto de corroborar y relacionar los aspectos estructurales de los molares primarios observados con MO y MEB y aplicar las técnicas de histoquímica microanalítica para determinar los patrones cuantitativos de mineralización del esmalte y dentina. Se utilizó un total de 30 molares (1º y 2º) clínicamente sanos, exfoliados. El estudio para microscopía óptica (MO) fue mediante la técnica por desgaste y cortes procesados y metalizados para la electrónica de barrido (MEB). En el esmalte se identificó la zona aprismática periférica, la línea neonatal, abundantes husos, conductillos dentinarios remanentes y microdefectos (laminillas o cracks de morfología y longitud variables). La dentina se caracterizó por la amplitud de los túbulos y escasa o nula dentina intertubular a nivel circumpulpar. El microanálisis con energía dispersiva de rayos X puso de relieve que el índice calcio/fósforo, tanto en esmalte como en dentina, alcanza el valor de 1.7, lo que sugiere que en la configuración de los cristales de apatita existen aniones carbonato. Los hallazgos de frecuentes microdefectos y la presencia de numerosas estructuras sin esmalte (husos y conductillos penetrantes) en la conexión amelodentinaria, especialmente en la porción coronaria oclusal nos advierte de los cuidados o precauciones a tomar en el momento de usar ácidos grabadores. Asimismo, la existencia de patrones de mineralización similares entre elementos primarios y permanentes, permite inferir que la terapéutica odontológica basada en la naturaleza de lamineralización podría aplicarse con idénticas pautas, pero respetando las variaciones estructurales respectivas
Subject(s)
Child, Preschool , Child , Dental Enamel , Dentin , Molar , Tooth, Deciduous , Electron Probe Microanalysis , Histocytochemistry/methods , Microscopy, Electron, Scanning , Microscopy, Polarization , Evaluation Studies as Topic , Data Interpretation, StatisticalABSTRACT
Evolutionary, structural, ultrastructural and cytochemical studies (PAS, alcian blue, toluidine blue, Ruthenium red) were performed in chick tongues 7 to 19 days development, with the aim of observing the histomorphological changes during growth and differentiation. At 7 days the tongue was covered by a flat epithelium without cornification, with four cell lines. As an axis was observed a central hyaline-cartilaginous skeleton surrounded by mesenchyma. Since 11 days appeared glandular buds and canalized cell cords united trough complexes. At 15 days the epithelial thickness increased remarkably. The subepithelial connective tissue, already notably differentiated, formed papillae. Glandular acini contained PAS positive, alcianophilic, metachromatic and positive ruthenium red substance. Ultrastructurally, glands showed clear cells, with decreased electronic density and organoids randomly distributed and dark cells having electrodense cytoplasm and more organized organoids. At 19 days the epithelium was cornified in the tongue anterior half. A net increment of glycoconjugates was detected in glands. These observations show: 1) lingual glands secrete mucins since 15 days of embryonic development; 2) the cornified anterior epithelium is the result of a genetic pattern and not of a later functional adaptation to the type of feeding (grain eating birds).
ABSTRACT
The structural and histochemical patterns of the salivary mesenchyma were analysed in relation to the epithelium of the labial glands during the embryonic development to correlate the structural and histochemical characteristics in both tissues during the histogenesis. Samples of human fetal lips were analysed using H/E, PAS, Cason, Alcian blue, Toluidine blue and Methenamine/silver. The process of glandular histogenesis begun between 8 to 10 weeks. The mesenchyma surrounding the glandular buds had PAS positive granulations which were also alcianophilic, metachromatic and periodatoreactive. Periodatoreactive collagenous fibrillae, reticular cells and nervous fibers of considerable diameter were observed. Basement membranes were PAS positive, alcianophilic and discontinuous. At 12 weeks the mesenchyma differentiated as loose connective tissue which produced a delicate periglandular capsule with fibroblast and collagenous fibrillae. From 20 to 24 weeks the acini were structurally and histochemically differentiated as serous, mucous and mixed. It was postulated that the periglandular mesenchyma would play and important role in the morphogenetic process in relation to the histochemical identification of molecules which have a specific biological functions in the epithelium-mesenchyma interactions during organogenesis.