RESUMO
It is not well-understood how low-laser therapy affects the skin of the applied area. This study analyzes skin of the masseteric region of mice from the HRS/J strain after three different application regimens (three, six or ten applications per regimen) of low intensity laser at 20 J/cm(2) and 40 mW for 20 sec on alternate days. Three experimental groups according to the number of laser applications (three, six or ten) and three control groups (N = 5 animals for each group) were used. On the third day after the last irradiation, all animals were sacrificed and the skin was removed and processed to analyze the relative occupation of the test area by each epithelial layer and the aspects of neovascularization. Data were submitted to statistical analyzes. The irradiated groups compared to their respective controls at each period of time, showed no significant difference in relative occupation of the test area by the layers and epithelium areas for three and six applications, but for ten applications, a significant decrease (P < 0.05) in the basal and granulosum layers, and epithelium areas were found. From the comparisons of the three irradiated groups together, the group with six laser applications showed statistical difference (P < 0.05) in total epithelium and on the layers. Vascular endothelial growth factor (VEGF) and VEGFR-2 immunoreactivities were similar for the control and irradiated groups. Results suggested a biostimulatory effect with low risks associated with superficial tissues, when the treatment aims the deeper layers after six applications.
Assuntos
Epitélio/efeitos da radiação , Terapia com Luz de Baixa Intensidade , Músculo Masseter/efeitos da radiação , Morfogênese/efeitos da radiação , Neovascularização Fisiológica/efeitos da radiação , Pele/efeitos da radiação , Animais , Relação Dose-Resposta à Radiação , Epitélio/irrigação sanguínea , Epitélio/metabolismo , Técnicas Imunoenzimáticas , Masculino , Músculo Masseter/irrigação sanguínea , Músculo Masseter/citologia , Camundongos , Camundongos Pelados , Pele/irrigação sanguínea , Pele/citologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
OBJECTIVES: The aim of the present investigation is to examine if the histological maturation of the neuromuscular junction in the masseters of human fetuses has already begun by the 12-th week of gestation or not. MATERIAL AND METHODS: Twenty-four masseter muscles from 14 human fetuses at gestational age 12 weeks were divided into two groups. In the first group, muscle sections were stained with Bielschowsky and Holzer stains for examination of neurofibrils and glial cells respectively. In the second group, rhodamine and fluorescein conjugated alpha-bungarotoxin were used to detect nicotinic receptors and anti-GAD for neuronal terminals. RESULTS: It was observed the presence of one axon for each end-plate and glial cells spread over a branched axon. The nicotinic receptors clustered in the neuromuscular junction, neuronal terminals and large oval nucleus were detected. CONCLUSIONS: These observations suggest that the maturation of the neuromuscular junctions of the masseter muscles in the human fetuses has already begun at the 12-th week of gestation.