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Rocha E.,University of Porto | Rocha E.,The Interdisciplinary Center | Rocha M.J.,The Interdisciplinary Center | Rocha M.J.,Superior Institute of Health science North | And 4 more authors.
Microscopy Research and Technique | Year: 2010

Sex differences exist in fish hepatocytes, but studies for characterizing their cytology throughout the breeding cycle are still scarce; suggesting changes, but most lacking quantitative data. To address this limitation, to complement baseline data generated from the brown trout model, and to prove that sex-specific seasonal changes exist, we made an unbiased stereological evaluation of the hepatocytic cytoplasm. Unprecedentedly for fish liver, the stereological design was exempt from model (biased) assumptions. Five (3 years old) animals per sex were studied in endogenous vitellogenesis, exogenous vitellogenesis, and spawning season end. Liver pieces for analysis were systematically sampled. Stereology was done in transmission electron microscopy (TEM) micrographs. Primary data generated relative volume estimates of the major cytoplasmic components. Such values were used for deriving absolute volumes (per cell and per liver). Lipid droplets did not show changes. As to other targets, trends at cell and liver levels were not always equal. If the hepatocyte was the reference space, the contents in mitochondria, dense bodies, glycogen, and cytosol changed seasonally, in both sexes. If taking the liver as the reference, changes attained the Golgi apparatus and rough endoplasmic reticulum (RER), besides dense bodies, glycogen (in females), and cytosol. The components volumes (namely per liver) were often positively (negatively for glycogen) correlated with the ovary weight, disclosing new associations and implications in fish. While also offering gold-standard data for backing morphofunctional correlations and pathology, we revealed a new process by which females increase the amount of RER and Golgi throughout vitellogenesis, breaking from the idea on how this event happens in fish. © 2009 Wiley-Liss, Inc. Source


Jordanova M.,Ss. Cyril and Methodius University of Skopje | Rocha M.J.,University of Porto | Rocha M.J.,The Interdisciplinary Center | Rocha M.J.,Superior Institute of Health science North | And 3 more authors.
Ichthyological Research | Year: 2013

Quantitative microscopic studies of season- and breeding-related changes in the liver of farm-raised fish are very scarce, and those of wild fish populations are virtually nonexistent. Moreover, none of the available studies investigated breeding-related changes in hepatic stroma, although it is already known that changes might exist in the parenchyma. To the best of our knowledge, ours is the first study using wild adult Ohrid trout females to evaluate quantitative influences of the breeding cycle on the volumes of the two liver compartments-parenchyma and stroma. Quantitative microscopy (stereology) using light microscopy was supplemented with semi-quantitative and quantitative analyses of hepatocyte cytology to express in numbers the seasonal changes in the extent of vacuolated versus basophilic cytoplasm. The liver volume and that of each compartment changed from that at the time of pre-vitellogenesis to the end of the spawning season. The changes in total volumes of parenchyma and stroma-increasing from pre-vitellogenesis to late vitellogenesis-followed the changes in total liver volume. Despite all the changes in total volumes, no differences existed in the relative proportions between the two major compartments. After spawning, the stromal volume continued to increase while that of the parenchyma reduced despite no detectable statistically significant impacts on the liver volume. Changes in both the liver and parenchyma volumes were correlated with the gonadosomatic index and plasma oestradiol levels. With this study, we first establish that fish liver remodelling might also occur in the stroma. When comparing Ohrid trout with other fish species, we noted interspecies similarities and differences with regard to the hepatocyte cytology during the breeding cycle. In our study, the semi-quantitative and stereological studies revealed that, from pre-vitellogenesis to post-spawning, although cytoplasmic vacuolation of the hepatocytes decreased, the basophilia increased. Overall, these cytological changes were only partially in agreement with the data from other trout studies. We believe that this is because of intrinsic interspecies differences in association with natural conditions. Thus, establishing normal patterns is crucial, at least for flagship species, namely to support interpretation of histopathological changes in biomonitoring. © 2012 The Ichthyological Society of Japan. Source


Silva P.,Superior Institute of Health science North | Barbosa J.,Superior Institute of Health science North | Nascimento A.V.,Superior Institute of Health science North | Faria J.,Superior Institute of Health science North | And 2 more authors.
Cell Proliferation | Year: 2011

Accurate chromosome segregation relies on activity of the spindle assembly checkpoint, a surveillance mechanism that prevents premature anaphase onset until all chromosomes are properly attached to the mitotic spindle apparatus and aligned at the metaphase plate. Defects in this mechanism contribute to chromosome instability and aneuploidy, a hallmark of malignant cells. Here, we review the molecular mechanisms of activation and silencing of the spindle assembly checkpoint and its relationship to tumourigenesis. © 2011 Blackwell Publishing Ltd. Source

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