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1.
Eur J Histochem ; 56(2): e24, 2012 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-22688305

RESUMO

The replacement of the calcified cartilage by bone tissue during the endochondral ossification of the mandibular condyle is dependent of the resorbing activity of osteoclats. After partial resorption, calcified cartilage septa are covered by a primary bone matrix secreted by osteoblasts. Osteoadherin (OSAD) is a small proteoglycan present in bone matrix but absent in cartilage during the endochondral ossification. The aim of this study was to analyze the effect of alendronate, a drug known to inhibit bone resorption by osteoclasts, on the endochondral ossification of the mandibular condyle of young rats, by evaluating the distribution of osteoclasts and the presence of OSAD in the bone matrix deposited. Wistar newborn rats (n=45) received daily injections of alendronate (n=27) or sterile saline solution as control (n=18) from the day of birth until the ages of 4, 14 and 30 days. At the days mentioned, the mandibular condyles were collected and processed for transmission electron microscopy analysis. Specimens were also submitted to tartrate resistant acid phosphatase (TRAP) histochemistry and ultrastructural immunodetection of OSAD. Alendronate treatment did not impede the recruitment and fusion of osteoclasts at the ossification zone during condyle growth, but they presented inactivated phenotype. The trabeculae at the ossification area consisted of cartilage matrix covered by a layer of primary bone matrix that was immunopositive to OSAD at all time points studied. Apparently, alendronate impeded the removal of calcified cartilage and maturation of bone trabeculae in the mandibular ramus, while in controls they occurred normally. These findings highlight for giving attention to the potential side-effects of bisphosphonates administered to young patients once it may represent a risk of disturbing maxillofacial development.


Assuntos
Alendronato/farmacologia , Conservadores da Densidade Óssea/farmacologia , Calcificação Fisiológica/efeitos dos fármacos , Côndilo Mandibular/crescimento & desenvolvimento , Animais , Cartilagem/citologia , Cartilagem/crescimento & desenvolvimento , Cartilagem/metabolismo , Matriz Extracelular/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Feminino , Masculino , Côndilo Mandibular/citologia , Côndilo Mandibular/metabolismo , Osteoblastos/citologia , Osteoblastos/metabolismo , Osteoclastos/citologia , Osteoclastos/metabolismo , Proteoglicanas/metabolismo , Ratos , Ratos Wistar
2.
Eur J Oral Sci ; 108(1): 74-7, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10706481

RESUMO

Adequate preservation of the cells and matrix of mineralising tissues remains difficult, as organic components and initial mineral deposits may be lost during conventional processing for electron microscopy. In this study, we have reduced significantly the processing time using microwave irradiation. Rat molar tooth germs were fixed in 4% glutaraldehyde + 4% formaldehyde with 0.1 M sodium cacodylate in a laboratory microwave oven for two periods of 20 s with a maximal temperature of 37 degrees C. After conventional washing and post-fixation, specimens were dehydrated in graded ethanols under microwave irradiation for a total of 7 min 20 s. For comparison, some specimens were processed by conventional methods. After embedding, ultrathin sections were examined by electron microscopy. In differentiating ameloblasts and odontoblasts, plasma membranes, mitochondria, rough endoplasmic reticulum, the Golgi complex, together with all other cytoplasmic organelles exhibited excellent preservation. Microtubules, microfilaments and coated vesicles were particularly evident. Crystal-like mineral deposits were conspicuously present in relation to dentine matrix vesicles and collagen fibrils as well as in enamel matrix. The matrix of forming enamel had a globular electron-lucent appearance. It is concluded that this is a rapid method which provides a preserved or even improved morphology.


Assuntos
Micro-Ondas , Fixação de Tecidos/métodos , Germe de Dente/embriologia , Germe de Dente/ultraestrutura , Ameloblastos/ultraestrutura , Animais , Citoplasma/ultraestrutura , Odontoblastos/ultraestrutura , Ratos , Fixação de Tecidos/instrumentação
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