RESUMO
Electron microscopic analysis of mineralized tissues like bone and dentin is essential for understanding of cell-cell/cell-matrix interactions, and the three-dimensional organization of these tissues. This chapter describes a few methods to process mineralized tissues obtained from different sources for ultrastructural analysis by transmission electron microscopy.
Assuntos
Osso e Ossos/diagnóstico por imagem , Técnicas de Preparação Histocitológica/métodos , Microscopia Eletrônica de Transmissão/métodos , Animais , Osso e Ossos/ultraestrutura , Técnicas de Preparação Histocitológica/instrumentação , Humanos , Camundongos , Microscopia Eletrônica de Transmissão/instrumentaçãoRESUMO
This chapter describes procedures to process mineralized tissues obtained from different sources for transmission electron microscopy (TEM). Methods for fixation, resin embedding, staining of semi-thin sections and ultrathin sections are presented. In addition, attention will be paid to processing of cultured bone explants for TEM analysis.
Assuntos
Osso e Ossos/ultraestrutura , Microscopia Eletrônica de Transmissão/métodos , Animais , Humanos , Microtomia/métodos , Coloração e Rotulagem/métodos , Inclusão do Tecido/métodos , Fixação de Tecidos/métodosRESUMO
Although the connective tissues of the periodontium are subject to a high turnover rate, no conclusive evidence has yet emerged that periodontal collagen turnover is essential for the eruption of teeth or for root elongation. These processes were studied in mice deficient in MT1-MMP, a membrane type matrix metalloproteinase essential for remodeling of soft tissue-hard tissue interfaces. Mandibular first molars of deficient mice and their wild-type littermates were subjected to stereological analysis in order to assess root length, eruption and the volume density of phagocytosed collagen in periodontal ligament fibroblasts. The data showed that both eruption and root elongation were severely inhibited in animals lacking the enzyme. We also found, in periodontal ligament fibroblasts from MT1-MMP-deficient mice, a massive age-related accumulation (up to 60-fold over controls) of collagen fibril-containing phagosomes. Phagolysosomes, which represent the next downstream step in collagen fibril degradation by the lysosomal pathway, did not accumulate. These observations indicate that MT1-MMP plays a central role in periodontal remodeling. The stunted root growth and the failure to erupt indicate the important role of the enzyme in tooth development.
