Little information is available on the pathogenesis of fluorosis during the fetal and initial postnatal period. In the present study, female rats received 0 (control), 7 or 100 ppm of sodium fluoride in drinking water, one week before breeding and throughout gestation and nursing periods. The hemimandibles of the offspring were collected at 0, 7 and 14 days of postnatal life (n = 5) and processed for morphological analyses by light and electron microscopy, immunohistochemical analysis for amelogenin and morphometric study of enamel matrix and ameloblasts of incisors. The results showed a decrease in matrix production at the secretory phase at all study periods for the 100 ppm group. In this same group, the secretory ameloblasts showed reduction of enamel matrix secretion, disorganization of mitochondrial crests, large vacuoles at the apical portion of the cytoplasm, retention of intracisternal material and dilatation of some cisterns in the rough endoplasmic reticulum. In the groups of animals aged 7 and 14 days, analysis of variance showed significant reduction (p<0.05) in cytoplasmic volume of 23.80% and 24.75%, respectively, in relation to the control group. The smooth-ended maturation ameloblasts exhibited a large number of vacuoles with electron-dense endocytic matrix, suggesting a delay in the resorption process. Immunohistochemical analysis showed no difference in the intensity and labeling pattern of the enamel matrix in any study group. Interestingly, in offspring at the age of 14 days for the 7 ppm group, there was an increase in the matrix length at the secretory phase. Therefore, part of the excessive dose of sodium fluoride given to the mother in drinking water can reach the offspring through the placenta and mother's milk, causing morphological changes in ameloblasts and suggesting a reduction in secretion and a delay in matrix resorption.

Poucos estudos demonstram as reações patológicas devidas à inalação de fumaça pelas vias aéreas de ratos. OBJETIVO: Estudar e analisar os possíveis efeitos histopatologicos produzidos pela inalação crônica de fumaça de cigarro nas pregas vocais de ratos. DESENHO DE ESTUDO: Experimental. MATERIAL E MÉTODOS: 36 ratos masculinos (Rattus norvergicus Wistar), de 60 dias de idade, foram mantidos em gaiolas e expostos à inalação da fumaça produzida por 10 cigarros, 3 vezes ao dia, 7 dias por semana, para períodos de 25, 50 e 75 dias, e os controles respectivos. Os animais foram sacrificados e as suas laringes dissecadas e submetidas a análise histológica com coloração de Hematoxilina e Eosina e analisados através de microscopia simples. RESULTADOS: Os ratos expostos ao cigarro exibiram menor (p <0,05) massa corporal que o grupo controle. Havia hiperplasia e metaplasia escamosa na extremidade livre da prega vocal e hiperplasia escamosa na porção mediana da prega vocal em todos os 3 períodos de estudo. Além disso, o grupo de 50 dias revelou metaplasia com queratinização nesta área. Não foram observadas alterações morfológicas em outras áreas da laringe e reação inflamatória da lâmina propria. CONCLUSÃO: Foi concluído que a inalação passiva de fumaça de cigarro rende mudanças morfológicas importantes no epitélio da prega vocal que podem, eventualmente, progredir para neoplasia.

Few studies have demonstrated the pathologic reactions yielded by smoke inhalation on the airway in rats. AIM: The aim of this study was to analyze the possible histopathological effects produced by chronic cigarette smoke inhalation on the vocal folds of rats. STUDY DESIGN: Experimental. MATERIAL AND METHOD: 36 male rats (Rattus norvergicus Wistar strain), aged 60 days, were kept in cages and exposed to inhalation of the smoke produced by 10 cigarettes lit 3 times a day, 7 days a week, for periods of 25, 50 and 75 days, and their respective controls. Thereafter the animals were killed and their larynxes were dissected and submitted to histological processing for achievement of histological sections, which were stained with Hematoxylin and Eosin and analyzed by light microscopy. RESULTS: The rats exposed to smoke displayed smaller (p< 0,05) body mass than the control group. There was hyperplasia and squamous metaplasia in the free edge of the vocal fold and squamous hyperplasia on the middle portion of the vocal fold in all 3 study periods. Moreover, the 50-day group revealed keratinizing metaplasia in this area. Morphological alterations in other areas of the larynx and inflammatory reaction of the lamina propria were also not observed. CONCLUSION: It was concluded that the passive inhalation of cigarette smoke yields important morphological changes in the vocal fold epithelium, which may progress to neoplasia.