Navegando por Palavras-chave "amelogenesis"

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Apoptosis 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 Grossa
    When 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.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Macrophages and apoptosis in the stellate reticulum of the rat enamel organ
    (Cambridge Univ Press, 2000-08-01) Baratella, Liriane [UNIFESP]; Arana-Chavez, V. E.; Katchburian, Eduardo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Ponta Grossa
    Tooth germs of upper first molars of 1, 3, and 5-d-old rats, fixed in formaldehyde, were stained for the detection of apoptosis by the TUNEL method, and by the ate-dye method for the demonstration of acid phosphatase. for conventional light and electron microscopy the specimens were fixed in glutaraldehyde-formaldehyde and embedded in glycol methacrylate and Araldite. Results showed that macrophages, present in the stellate reticulum, contained basophilic bodies and TUNEL-positive globules, i.e. apoptotic bodies, in their interior. Macrophages also possessed strong acid phosphatase activity. Electron microscopy showed the presence of large vacuoles inside the macrophages containing dense fragmented material. Taken together these results suggest that the intra-epithelial macrophages of the stellate reticulum engulf apoptotic bodies.