ABSTRACT
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 percent and 24.75 percent, 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.
ABSTRACT
The postnatal development of the guinea pig pancreas (Cavia porcellus) from 2 to 140 days old was studied stereologically by light microscopy. During this period, the pancreatic volume increased 805 percent. The compartmental volumes of the acini, intercalated ducts, excretory ducts, islets of Langerhans and stroma increased 756 percent, 1,372 percent, 1,591 percent, 3,393 percent and 793 percent, respectively, whereas the total external surfaces of the acini, intercalated ducts and excretory ducts increased 542 percent, 1,667 percent and 1,002 percent, respectively. This growth involved increases of 361 percent, 74 percent, 1,355 percent and 673 percent in the total number of acinar, centroacinar, intercalated duct and excretory duct cells, respectively. In the same period, the mean volume of acinar cells increased 210 percent. These results indicate that the growth of the acinar compartmental volume involves a significant proliferative activity of the acinar cells and an increase in the individual cell volume. Analysis of the surface-to-volume ratio during this growth showed that the acini increased significantly in size. On the other hand, the growth of the parenchymal structures was accompanied by a reduction on interacinar connective tissue spaces and by the final organization of the interlobar and interlobular septa.
Subject(s)
Animals , Pancreas , Guinea Pigs , Pancreas , SwineABSTRACT
The submandibular glands of rats raised at room temperature show daily and seasonal variations. To quantify these variations, the submandivular glands of male Wistar rats were collected at 4h intervals over a 24h period in the summer and winter and processed for histological analysis. Gland weight decreased 37 per cent (P<0.01) in the winter and 13 per cent in the summer. The volume of the acinar compartment decreased 73 per cent (P<0.01) between midnight and 4 a.m. in the winter and 38 per cent (P<0.01) between 8 p.m. and midnight in the summer. In contrast, the volume of the stroma increased about 164 per cent (P<0.01) between midnight and 4 a.m. in the winter and by 10 per cent (P<0.01) between 8 p.m. and midnight in the summer. the volume of the duct system generally remained constant, although in the winter the convoluted granular tubules diminished 44 per cent (P<0.01) between midnight and 4 a.m. Although the volume of the intercalated ducts remained constant over 24h in both seasons, there was a 49 per cent decrease in winter compared to summer (P<0.01). These results indicate that the large changes in gland weight were caused mainly by variation in the volume of the acini, convoluted granular bubules ans stroma. The morphological variations were much more pronounced in winter than in summer and this affected the daily saliva production.
Subject(s)
Animals , Male , Rats , Circadian Rhythm , Submandibular Gland/anatomy & histology , Rats, WistarABSTRACT
As glândulas sulinguais do rato albino crescem marcadamente nos primeiros 40 dias de vida pós-natal. Na presente pesquisa estudamos a participaçäo da atividade proliferativa e do aumento do volume celular neste crescimento. A atividade proliferativa foi medida pelo aumento do DNA total avaliado bioquimicamente e o aumento do volume celular foi determinado por métodos morfométricos. A análise dos resultados mostrou que: a) o DNA aumentou 717 por cento (P < 0,01) no período de 2 a 40 dias de vida pós-natal; b) o volume das células acinosas mucosas exibiu flutuaçöes estatisticamente näo significativas até o 15§ dia, sofrendo, a partir daí, um aumento de 101 por cento (P < 0,05) até o 40§ dia; c) o volume das células das semiluas serosas mostrou decréscimo de 27 por cento (P < 0,05) no período de 10 a 15 dias, seguido de aumento de 71 por cento (P < 0,05) no período de 15 a 30 dias. Esses resultados indicam que o aumento significativo de massa de glândulas sublinguais do rato durante o período inicial de vida pós-natal, ocorreu principalmente por atividade proliferativa, e também, com menor participaçäo, por aumento de volume celular, notadamente das células acinosas mucosas.