Histology and histopathology Vol.11, nº 3 (1996)
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- PublicationOpen AccessFine structure of the pecten oculi in the Austral ian Gala h (Eolophus roseicapillus) (Aves)(Murcia : F. Hernández, 1996) Braekevelt, Charlie R.; Richardson, K.C.The pecten oculi of the Australian galah (Eolophus r.oseicapillus) has been examined by both light and electron microscopy. In this species the pecten is large relative to the size of the eye and is of the pleated type. It consists of 20-25 accordion folds that are joined apically by a bridge of tissue which holds the pecten in a fan-like shape widest at its base. Within each fold are many melanocytes, numerous capillaries as well as larger supply and drainage vessels. The capillaries are extremely specialized for transport functions and display extensive microfolds on both their luminal (inner) and abluminal (outer) borders. Except for the nuclear region which also contains most of the organelles, the endothelial cell bodies are extremely thin. These capillaries are surrounded by thick fibrillar basal laminae which are felt to be structurally important. Pericytes are a common feature within the basal lamina of capillaries. The numerous pleomorphic melanocytes which more or less surround the capillaries are also presumed to be important in structural support of the pecten. The pecten represents a supplementary retinal circulation and is comparable to the falciform process of some teleosts, the conus papillaris of reptiles, the supraretinal vessels of amphibians and some teleosts and the intraretinal vessels of mammals, al1 of which are felt to be alternative methods of bringing nutrients to the inner retina.
- PublicationOpen AccessComparative in vivo and in vitro models to approach the cellular basis of endotoxic shock. The role of sinusoidal liver cells(Murcia : F. Hernández, 1996) Pagani, R.; Portolés, M.T.; Arahuetes, Rosa María; Ainaga, M.J.; Machín, Celia; Rúa, CarmenDuring endotoxic shock, the liver exerts a lipopolysaccharide (LPS) clearance function with the participation of both parenchymal and sinusoidal cells. Liver damage could be caused by LPS direct action, hypoxia and/or inflammatory mediators released by Kupffer cells. The aim of this study is to establish an experimental model that could allow us to understand the direct E. coli O1 1 l:B4 LPS action on sinusoidal cells. A comparative study was carried out, in vivo and in vitro, using either a rat reversible endotoxic shock model or sinusoidal cell cultures. The LPS was found to induce important and similar morphological alterations both in vivo and in vitro, specially in Kupffer cells. These cells present mitochondrial damage, nuclear membrane swelling, and increased number of phagosomes, including lamellar bodies. An immunocolloidal gold technique shows, in vitro, the LPS mainly located on Kupffer cell membrane and in phagosomes. The LPS binding to membrane, as a primary step of Kupffer cell activation, increases the phagocytosis. This effect could be related to a decrease of fluidity on the externa1 membrane portion.
- PublicationOpen AccessOsteoclast differentiation antigen(Murcia : F. Hernández, 1996) Kukita, T.; Kukita, A.Osteoclasts are the primary cells which perform bone resorption. The origin of these multinucleated giant cells is the haematopoietic stem cells. The differentiation pathway of the osteoclasts has so far been well studied and the cell-lineage of these bone resorbing cells is considered to be close but not identical to the monocytes/macrophages. Owing to the development of in vitro culture systems for evaluating osteoclast differentiation, it has been elucidated that various cytokines are involved in the differentiation of the osteoclasts. However, there is still ambiguity concerning the molecular mechanism of the differentiation of the osteoclasts. One approach for clarifying the molecular mechanism is to find unique antigen molecules involved in the process of osteoclast differentiation. In this review article, we introduce such immunological studies concerning osteoclast differentiation. We also refer to our recent establishment of a panel of monoclonal antibodies recognizing rat osteoclasts. One of the monoclonal antibodies recognizes cell surface antigen (Kat 1 -antigen) expressed on cells in osteoclast-lineage and not on monocytes/macrophages. Cross-linking of the cell surface antigen using this monoclonal antibody showed that the Katl-antigen is the unique cell surface molecule involved in the regulation of the affinity of the calcitonin receptor and also involved in the modulation of the bone resorption. In this review article, we overview, the current issues which should be elucidated for understanding the differentiation and activation of the osteoclasts. We further emphasize the utility of the immunological approach for solving these current target issues.
- PublicationOpen AccessErythrophagocytosis by brown adipocytes of rat interscapular tissue(Murcia : F. Hernández, 1996) Radovanovic, J.; Korac, A.; Davidovic, V.; Koko, V.; Todorovic, V.In this investigation the following phenomena were observed: 1. Rat interscapular brown adipocytes were found to be capable of erythrophagocytosis; 2. Before leaving the capillary lumen, erythrocytes took some material from the blood plasma by endocytosis and passed the endothelial junction canying endocytotic vacuole. Some erythrocytes were in transit: the so-called «head» was in the process of engulfment by brown adipocytes while the rest of the cell had not left the capillary lumen. Fragmentation of erythrocytes was observed during passage through the endothelial junction as well as in the cytoplasm of adipocytes. 3. In some brown adipocytes erythrocytes retained the same shape as in the capillary, but in many cases they exhibited unusual form. Intracytoplasmic erythrocytes were seen in a semithin sections stained with toluidine blue. 4. Erythrocytes either became cells which phagocytized mitochondria and lipid droplets before their transformation into lipofuscin bodies or they were degraded into ferritin-like particles observed (on unstained sections) in the mitochondrial matrix, intercristal space, on the periphery of lipid droplets and in brown adipocyte cytoplasm.
- PublicationOpen AccessHistoenzymological detection of sialic acids in the rodent salivary glands(Murcia : F. Hernández, 1996) Accili, Daniela; Gabrielli, M.G.; Menghi, Giovanna; Materazzi, G.Sections from the major salivary glands of rats and mice were used to locate, charactecize and compare sialoglycoconjugates by means of lectin histochemistry, sialidase digestion, periodate oxidation and potassium hydroxide deacetylation. The gland sialylated macromolecules contained the terminal dimers sialic acid-B-galactose and sialic acid-a-N-acetylgalactosamine but differed in the varieties of sialic acids and the linkages of sialic acids to penultimate sugars. Indeed, the submandibular and parotid glands exhibited a notable occurrence of periodate labile sialic acids with C7 andlor C8 andlor C9 acetyl groups in their polyhydroxyl chains. In particular, C9 acetylated sialic acids were mostly linked a2-6 to B-galactose. The sublingual glands, instead, were strongly characterized by a presence of C9 acetylated sialic acids bound a2-3 to B-galactose. Also, sialic acids with O-acetyl substituents at C4 were evident in the mouse parotid gland and in the rat submandibular and sublingual glands. The great variety of sialoderivatives expressed by the rodent salivary glands was correlated with the differential involvement of these compounds in lubricating and defensive processes. Sex-related differences regarding the sialic acid location, acetylation degree and linkage were shown in the submandibular glands of both species.