Navegando por Palavras-chave "transmission electron microscopy"
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- ItemSomente MetadadadosApoptosis in the early involuting stellate reticulum of rat molar tooth germs(Springer, 1999-07-01) Baratella, L.; Arana-Chavez, V. E.; Katchburian, E.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Ponta GrossaWhen the enamel organ of the rat tooth germ is fully developed at the tip of the prospective cusp, amelogenesis begins, and at this site the overlaying stellate reticulum begins its involution. During the involution process, there is a gradual decrease in intercellular spaces, invasion by blood vessels, appearance of macrophage-like cells and reduction in the number of stellate reticulum cells. Since reduction or disappearance of cells during embryonic development in organs and tissues has been shown to occur by apoptosis, we decided to examine early involuting regions of the stellate reticulum in the hope of detecting apoptosis. for this purpose, upper first molars of Wistar newborn rats aged 1 and 3 days were fixed in formaldehyde for the TUNEL method and in glutaraldehyde-formaldehyde for light and electron microscopy. Paraffin sections revealed TUNEL-positive structures, i.e. brown-yellow-stained bodies, in the central portion of the stellate reticulum, and next to the outer enamel epithelium and stratum intermedium. Examination of ultrathin sections confirmed the TUNEL findings: some stellate reticulum cells showed nuclei containing crescent-like electron-opaque condensed masses of peripheral chromatin, typical of apoptosis. Also, apoptotic bodies of various sizes and appearances were frequently observed within stellate reticulum cells. We should like to suggest that apoptosis is associated with the reduction in the number of cells during regression of the reticulum.
- ItemSomente MetadadadosExperimental Leishmania (L.) amazonensis leishmaniasis: Characterization and immunogenicity of subcellular fractions(Taylor & Francis Inc, 2007-01-01) Valle, T. Zaverucha do; Gaspar, Emanuelle Baldo [UNIFESP]; Souza-Lemos, C.; Souza, C. S. F.; Marquez, F. B. Zamora; Baetas-da-Cruz, W.; d'Escofier, L. N.; Corte-Real, S.; Calabrese, K. S.; Costa, S. C. Goncalves da; Inst Oswaldo Cruz; Universidade Federal de São Paulo (UNIFESP)A technique developed in Trypanosoma cruzi biochemical studies was successfully used to fractionate Leishmania (Leishmania) amazonensis promastigotes. Ultrastructural analyses revealed a membrane fraction (MF) associated to subpellicular microtubules, a ribosomal-rich microsomal fraction (MicF), and a flagellar fraction (FF) free of associated membrane. All fractions proved to be immunogenic through delayed type hypersensitivity reaction assays. Therefore, a protocol was designed to test whether these fractions could elicit a protective response in mice infected by L. (L), amazonensis. the protocol consisted of a BCG injection (as cellular immunity inducer), followed by cyclophosphamide (once its cytotoxic effect is over, this immunosupressor can increase the number of circulating leukocytes), then an injection with one of the fractions followed by a challenge. When compared to infected control animals, mice injected with any of the fractions presented a smaller footpad swelling, especially those injected with MicF or FF. Macroscopically, immunized mice under modulation by BCG presented no swelling. Histopathological studies performed on day 120 revealed fewer amastigotes and more intense inflammation in lesions of MicF and FF injected mice. Animals injected with MF presented an intermediate pattern. Parasite quantification corroborated these results. the results show that all fractions are potent immunostimulators, but MicF and FF have the strongest protective ability.
- ItemSomente MetadadadosUltrastructural and biochemical changes of the medial pterygoid muscle induced by unilateral exodontia(Elsevier B.V., 2008-07-01) Bazan, Emmanuel [UNIFESP]; Mardegan Issa, Joao Paulo; Watanabe, Ii-sei; Alberto Mandarim-de-Lacerda, Carlos; Aparecida Del Bel, Elaine; Iyomasa, Mamie Mizusaki; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Universidade do Estado do Rio de Janeiro (UERJ)The aim of the present study was to investigate the histological, biochemical and ultrastructural effects of occlusal alteration induced by unilateral exodontia on medial pterygoid muscle in guinea pigs, Cavia porcellus. Thirty (n = 30) male guinea pigs (450 g) were divided into two groups: experimental-animals submitted to exodontia of the left upper molars, and sham-operated were used as control. the duration of the experimental period was 60 days. Medial pterygoid muscles from ipsilateral and contralateral side were analyzed by histological (n = 10), histochernical (n = 10), and ultrastructural (n = 10) methods. the data were submitted to statistical analysis. When the ipsilateral side was compared to the control group, it showed a significantly shorter neuromuscular spindle length (P < 0.05), lower oxidative metabolic activity, and microvessel constriction, in spite of the capillary volume and surface density were not significantly different (P > 0.05). in the contralateral side, the neuromuscular spindles showed significantly shorter length (P < 0.05), the fibers reflected a higher oxidative capacity, the blood capillaries showed endothelial cell emitting slender sprouting along the pre-existing capillary, and significantly higher blood capillary surface density, and volume density (V-v = 89% Mann-Whitney test, P < 0.05). This finding indicated a complex morphological and functional medial pterygoid muscle adaptation to occlusal alteration in this experimental model. Considering that neuromuscular spindles are responsible for the control of mandibular positioning and movements, the professional should consider if these changes interfere in the success of clinical procedures in medical field involving stomatognathic structures. (c) 2007 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosUltrastructural features of the myotendinous junction of the sternomastoid muscle in Wistar rats: From newborn to aging(Wiley-Blackwell, 2012-09-01) Ciena, Adriano Polican; Yokomizo de Almeida, Sonia Regina; Bolina, Cristina de Sousa; Bolina-Matos, Regina de Sousa; Grassi Rici, Rose Eli; Pereira Da Silva, Marcelo Cavenaghi [UNIFESP]; Miglino, Maria Angelica; Watanabe, Ii-Sei; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)The myotendinous junction (MTJ) is a major area for transmitting force from the skeletal muscle system and acts in joint position and stabilization. This study aimed to use transmission electron microscopy to describe the ultrastructural features of the MTJ of the sternomastoid muscle in Wistar rats from newborn to formation during adulthood and possible changes with aging. Ultrastructural features of the MTJ from the newborn group revealed pattern during development with interactions between muscle cells and extracellular matrix elements with thin folds in the sarcolemma and high cellular activity evidenced through numerous oval mitochondria groupings. the adult group had classical morphological features of the MTJ, with folds in the sarcolemma forming long projections called finger-like processes and sarcoplasmic invaginations. Sarcomeres were aligned in series, showing mitochondria near the Z line in groupings between collagen fiber bundles. the old group had altered finger-like processes, thickened in both levels of sarcoplasmic invaginations and in central connections with the lateral junctions. We conclude that the MTJ undergoes intense activity from newborn to its formation during adulthood. With increasing age, changes to the MTJ were observed in the shapes of the invaginations and finger-like processes due to hypoactivity, potentially compromising force transmission and joint stability. Microsc. Res. Tech. 75:12921296, 2012. (C) 2012 Wiley Periodicals, Inc.
- ItemAcesso aberto (Open Access)Ultrastructure of the adhesion of bacteria to the epithelial cell membrane of three-day postnatal rat tongue mucosa: a transmission and high-resolution scanning electron microscopic study(Fundação Odontológica de Ribeirão Preto, 2007-01-01) Watanabe, Ii-sei; Ogawa, Koichi; Silva, Marcelo Cavenaghi Pereira da [UNIFESP]; Motoyama, Aracy Akiko; Kado, Eduardo Shigueaki; Lopes, Ruberval Armando; University of São Paulo Institute of Biomedical Sciences Department of Anatomy; Fukuoka University Department of Anatomy; Universidade Federal de São Paulo (UNIFESP); University of São Paulo School of Dentistry of Ribeirão Preto Department of Morphology and StomatologyTogue mucosa surface of 3-day postnatal rats was examined under transmission electron microscopy (TEM) and high-resolution scanning electron microscopy (HRSEM). For HRSEM analysis, the specimens were fixed in the same solution for 24 h, postfixed in 2% osmiun tetroxide, critical-point dried and coated with platinum-palladium. For TEM analysis, the specimens were fixed using modified Karnovsky solution and embedded in Spurr resin. The results revealed the presence of numerous microplicae in the membrane surface of keratinized epithelial cells to which groups of bacteria were attached. These bacteria were staphylococcus and coccus organized either in rows or at random, which were visualized in three-dimensional HRSEM images. At high magnification, the TEM images revealed the adhesion of bacteria to the cell membrane through numerous filamentous structures comprising the glycocalyx. The fine fibrillar structures rising from each bacterium and from cell membrane were clearly seen. These characteristics on bacteria structure may be used for future control or prevention of bacterial diseases and for installation of the oral native flora.