Histology and histopathology Vol.16, nº 2 (2001)
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- PublicationOpen AccessCell adhesion molecules in human osteoblasts: structure and function(Murcia : F. Hernández, 2001) Bennett, J.H.; Moffatt, S.; Horton, M.Osteoblasts and bone lining cells form a near continuous layer covering the bone surface and interactions between these cells and the organic matrix of bone are important determinants of osteoblast proliferation and differentiation. In addition, cells of the osteoblast-lineage form functional cornrnunications with each other, with the extra-cellular matrix and with osteocytes through cytoplasmic processes extending through canaliculi in the bone. Together, these cells form a network of putative importance in the regulation of skeletal homeostasis. Cell-cell and cell-matrix interactions are mediated by members of severa1 families of cell adhesion molecules, and knowledge of their interactions will be of fundamental importance in understanding the role of osteoblast in skeletal turnover . Here, the expression pattern of members of the major families of cell adhesion molecules by cells of the osteoblast lineage is reviewed. Special emphasis has been placed on human tissues. In addition, the possibility that cells at progressive stages of the osteoblast lineage have different profiles of cell adhesion molecule expression is explored, and the putative significance of cell-matrix interactions in human skeletal disease briefly discussed.
- PublicationOpen AccessHistological and histochemical observations in the stomach of the Senegal sole, Solea senegalensis(Murcia : F. Hernández, 2001) Arellano, J.M.; Storch, V.; Sarasquete, C.An histological and histochemical study was conducted on the stomach of adult Senegal sole, Solea senegalensis specimens. The stomach was made up of four distinct layers: mucosa, lamina propria-submucosa-, muscularis and serosa. Surface epithelial, glandular and rodlet cells were present in the mucosa. Cells of the columnar epithelium contained a basa1 nucleus. Numerous mitochondria, granular endoplasmic reticulum and Golgi apparatus consisting of severa1 parallel cisternae and vesicles were observed in the cytoplasm of these cells. The lysosomes were small, round and dense. The gastric glands were numerous in the pyloric and fundic regions but absent in the cardiac stomach. These glands were formed by two cell-types: light and dark cells. The light cells were characterised by numerous mitochondria, while dark cells had slightly fewer mitochondria and a tubulo-vesicular system. Rodlet cells similar to those observed in other teleostean fish were present among the epithelial cells. Although the epithelial cells of the mucosa contained a weak presence of neutral and acid mucopolysaccharides/mucosubstances, these substances were abundant in the lamina propria-submucosa. Proteins rich in arginine, lysine, cysteine and cystine were rarely present in the mucosa and lamina propriasubmucosa of stomach, while proteins rich in tyrosine were abundant in these layers. Acid phosphatase, and ATP-ase (pH 7.2 and 9.4) activities were detected in the mucosa and lamina propria-submucosa. Alkaline phosphatase activity was not detected.
- PublicationOpen AccessTumor cell "dead or alive": Caspase and survivin regulate cell death, cell cycle and cell survival(Murcia : F. Hernández, 2001) Suzuki, A.; Shiraki, K.Cell death and cell cycle progression are two sides of the same coin, and these two different phenomenons are regulated moderately to maintain the cellular homeostasis. Tumor is one of the disease states produced as a result of the disintegrated regulation and is characterized as cells showing an irreversible progression of cell cycle and a resistance to cell death signaling. Severa1 investigations have been performed for the understanding of cell death or cell cycle, and cell death research has remarkably progressed in these 10 years. Caspase is a nomenclature referring to ICEICED- 3 cysteine proteinase family and plays a central role during cell death. Recently, severa1 investigations raised some possible hypotheses that caspase is also involved in cell cycle regulation. In this issue, therefore, we review the molecular basis of cell death and cell cycle regulated by caspase in tumor, especially hepatocellular carcinoma cells.
- PublicationOpen AccessExpression of VEGF-C and activation of its receptors VEGFR-2 and VEGFR-3 in trophoblast(Murcia : F. Hernández, 2001) Dunk, C.; Ahmed, A.Placental villous development requires the co-ordinated action of angiogenic factors on both endothelial and trophoblast cells. Like vascular endothelial growth factor (VEGF), VEGF-C increases vascular permeability, stimulates endothelial cell proliferation and migration. In the present study, we investigated the expression of VEGF-C and its receptors VEGFR-3 and VEGFR-2 in normal and intrauterine growth-restricted (IUGR) placenta. Immunolocalisation studies showed that like VEGF and VEGFR-1, VEGF-C, VEGFR-3 and VEGFR-2 co-localised to the syncytiotrophoblast, to cells in the maternal decidua, as well as to the endothelium of the large placental blood vessels. Western blot analysis demonstrated a significant decrease in placental VEGF-C and VEGFR-3 protein expression in severe IUGR as compared to gestationallymatched third trimester pregnancies. Conditioned medium from VEGF-C producing pancreatic carcinoma (Suit-2) and endometrial epithelial (Hec-1B) cell lines caused an increased association of the phosphorylated extracellular signal regulated kinase (ERK) in VEGFR-3 immunoprecipitates from spontaneously transformed first trimester trophoblast cells. VEGF121 caused dosedependant phosphorylation of VEGFR-2 in trophoblast cells as well as stimulating DNA svnthesis. In addition. premixing VEGFl with Yheparin sÚlphate proteoglycan wtentiated trooho8ast oroliferation and the association Lf p h ~ s p hw~ith- t i~e V~E~GF R-2 receptor. VEGF165- mediated DNA synthesis was inhibited by anti-VEGFR- 2 neutralising antibody. The results demonstrate functional VEGFR-2 and VEGFR-3 receptors on trophoblast and suggest that the decreased expression of VEGF-C and VEGFR-3 may contribute to the abnormai villous development observed in IUGR placenta.
- PublicationOpen AccessThe hepatocytes of the brown trout (Salmo trutta f. fario):A quantitative study using design-based stereology(Murcia : F. Hernández, 2001) Rocha, E.; Monteiro, R.A.F.; Oliveira, M.H.; Silva, M.W.A stereological study was performed on brown trout hepatocytes aiming to disclose whether there are basic gender differences when minimal levels of sex hormones exist, and also to establish a platform for both interspecific comparisons and physiological correlations. We used the so-called "design-based stereology" (with no shape, size or orientation assumptions) and also some new related statistics. Twoyear- old brown trout were collected in April, and the livers were fixed by perfusion. From liver slicing to microscopical field selection, systematic sampling was used. Stereology was applied at light and electron microscopy. Target parameters were the relative and total hepatocyte number, the mean individual hepatocyte volume and surface, and also both relative and total volumes, and surfaces, either of organelles or of cell compartments. Observed variability was usually high, but the precision of estimates was proved to be globaily adequate facing the true biological variation amongst specimens. Females had more hepatocytes per liver ( 1 . 7 9 ~ 1 0v~s. 1 . 1 2~1 0~C) .o nsidering the individual hepatocytes, whereas no gender differences were detected in the cell volume, males had higher values of nuclear volume (199 vs. 151 pm3) and surface (170 vs. 131 pm2), endoplasmic reticulum volume I 1300 vs. 824 pm3), and microvilli volume (82 vs. 54 pm ) and surface (1445 vs. 975 pm2). However, when dealing with quantities per liver, gender differences were found only in the volumes of dense bodies (56 vs. 97 mm3) and of residual cytoplasm (169 vs. 341 mm3) - both volumes were higher in females. Functional implications of data are discussed, namely that females seem to have basic structural traits for coping with the later demands of breeding. Data also support that structural remodelling of hepatocytes occurs after breeding, urging to pursue seasonal studies (namely on lysosomes). We advanced the hypothesis that genders differ in microvilli surface just to maintain an optimal physiological surface-to-volume ratio. Interspecific similarities and differences were disclosed. For example, the number of hepatocytes/cm3 of parenchyma of brown trout was much lower than those reported in rainbow trout, but in both trouts femaies seem to have an higher cell number. In addition, when comparing the size of hepatocytes of brown trout with that from other fish and mammals it was suggested that major interspecific differences exist.