Histology and histopathology Vol. 9, nº 4 (1994)
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- PublicationOpen AccessVariety of sialic acids occurring in the bovine sublingual gland(Murcia : F. Hernández, 1994) Accili, Daniela; Gabrielli, M.G.; Menghi, GiovannaSialoglycoconjugates were investigated in the bovine sublingual gland by direct visualization of sialic acid with specific lectins (LPA, SNA) and by histochemical procedures combined with sialidase digestion and lectins. The most reactive histological sructures were found to be acini which contained glycoconjugates with terminal disaccharides consisting of sialic acid linked to galactose or N-acetylgalactosamine. Resistance to periodate oxidation was interpreted as demonstrating a relevant presence of C7, C8 and Cg acetylated sialic acids. KOH-Sialidase-DBA and KOHAlcian blue sequences allowed the identification of C4 acetylated sialic acids.
- PublicationOpen AccessMorphogenesis of normal human salivary gland cells in vitro(Murcia : F. Hernández, 1994) Azuma, M.; Sato, M.Primary cultured human salivary gland cells were transfected with ori-defective mutant DNA of SV40. Following 2-3 weeks of transfection, slowly expanding colonies consisting of small compact cells emerged, while mock-transfected cells did not grow any more and eventually entered crisis, followed by cell death. Using limited dilution technique, we isolated 4 cell clones with distinct morphology from a single colony. Morphological observation of cells cultured on plastic dishes precisely revealed the characteristics of the constituent cells of salivary gland; i.e., three cell clones showing cuboidal- (NS-SV-DC), spindle- (NS-SV-MC), and flattened morphology (NS-SV-SC) were similar to duct-, myoepithelial-, and squamous phenotype, respectively. A remaining cell clone, polygonal in shape and with numerous secretory granules (NS-SV-AC), resembled an acinar cell. Characterization of cell clones by ultrastructural exarnination and search for specific antigens showed the similarity of NS-SV-DC, NS-SV-MC, NS-SV-AC, and NS-SV-SC to duct, myoepithelial, acinar, and squamous cells, respectively. Anchorage-independent growth in soft agar and tumorigenicity in nude mice were not recognized in al1 cell clones. These results demonstrate that establishment of cell clones with duct-, myoepithelial-, acinar-, or squamous phenotype was accomplished in the in vitro system, and that based on the evaluation of colony-forming ability in soft agar and tumorigenicity in nude mice these cell clones can be considered to be non-tumorigenic. Using the above in vitro system, we examined the effect of a reconstituted basement membrane extract, Matrigel, on the morphogenesis of cultured normal human salivary gland cells. When NS-SV-DC or NS-SV-MC were seeded on Matrigel in serum-free culture conditions, they formed round or zona1 clusters on day 1; failing however, to develop into a salivary gland morphogenesis. Semithin sections of cell clones cultured on Matrigel exhibited multicellular aggregates on day 1, while on days 2 and 3 these cells lost both cell-cell and cell-Matrigel interactions and eventually entered crisis. In an attempt to understand the mechanism involved in this phenomenon, we have investigated proteolytic enzymes and their inhibitors secreted by cell clones. Although cell clones produced almost identical levels of gelatinases, they released increased amounts of plasminogen activators (PAs) as compared with a neoplastic human salivary gland cell line (HSG), which had already been demonstrated to differentiate into acinar cells when cultured on Matrigel. Obvious difference of expression leve1 of tissue inhibitor of metalloproteinases-1 (TIMP- 1) was not observed in these cells. However, secretion of PA inhibitors was elevated in NS-SV-MC when compared to NS-SV-DC. Neutralization of excess PAs by exogenously-added serine protease inhibitors corrected the aberrant morphogenesis of NS-SV-DC, but not that of NS-SV-MC, and allowed NS-SV-DC to form glandular-like structures. Thus, these results may suggest that a tightly regulated proteolytic activity is, in part, essential for in vitro morphogenesis of normal salivary gland duct cells.
- PublicationOpen AccessAngiogenesis: an update(Murcia : F. Hernández, 1994) Díaz-Flores, Lucio; Gutiérrez, Ricardo; Varela, H.Angiogenesis is the neovascularization or formation of new blood vessels from the established microcirculation. It is particularly important and indispensable in a large number of normal and pathological processes during pre- and post-natal life, including neoplasia, inflammation, wound repair and collaterization in response to ischemic stimuli. The current interest in the role of neovascularization in the transition from hyperplasia to neoplasia, as well as in the tumour growth and metastasis, has brought about a large number of studies on angiogenesis. The complex processes of neovascularization, quiescent in the adult organism, may occur rapidly in several circumstances, with the implication of the following events: a) endothelial cell (EC) and pericyte activation; b) basal lamina degradation; c) migration and proliferation of EC and pericytes; d) formation of a new capillary vessel lumen; e) appearance of pericytes around the new capillaries; f) development of a new basal lamina; g) capillary loop formation; h) persistence or involution, and differentiation of the new vessels; and i) capillary network formation and, eventually, organization into larger microvessels. The use of numerous "in vivo" and "in vitro" systems has facilitated the assessment of angiogenesis control, in which angiogenic (fibroblast growth factors, vascular endothelial growth factor, platelet endothelial growth factor, E series prostaglandin, angiogenin, monobutyrin) and antiangiogenic (cartilagederived angiogenic inhibitor, thrombospondin, protamine, platelet factor-4, interferon, angiostatic antibiotics, steroids) substances intervene. Heparin and heparin sulphate also play a key role in these mechanisms. A greater knowledge of angiogenesis control may lead to the development of a potential therapy in angiogenesis-related processes.
- PublicationOpen AccessCell types in the central nervous system infected by murine retroviruses: implications for the mechanisms of neurodegeneration(Murcia : F. Hernández, 1994) Wong, P.K.Y.; Yuen, P.H.Retroviruses are an important cause of neurologic disease in humans but the pathogenic mechanisms are poorly understood. To delineate pathogenic mechanisms in any neurologic disease in humans is extremely difficult and will continue to rely on the use of animal models. This review presents severa1 murine models to study the pathogenic mechanisms of neurodegenerative disease which manifest noninflammatory spongiform lesions in the CNS. The cell types in the CNS infected by these murine retroviruses and their role in disease induction are discussed.
- PublicationOpen AccessModifications of the dermis during scale regeneration in the lizard tail(Murcia : F. Hernández, 1994) Alibardi, LorenzoDuring scale morphogenesis in the regenerating tail of lizards (Anolis and Lampropholis) the structure of the dermis undergoes changes in relation to the ingrowth of epidermal papillae to form the new scales. Cell proliferation in the dermis, as revealed by the uptake of 3~-thymidinei,s high in the prescaling region of the regenerating tail but lower than the proliferation in the epidermis. Under the epidermis of the scaling region dermal cell proliferation rapidly drops down under the distal (apical) and proximal (caudal) sides of the infoldin epidermal papillae. Dermal fibroblasts take up g ~ - p r o l i n ein high amounts, especially in the forming deep dermal layer, where many collagen fibrils are laid down forming dense connective. Electron microscopic study revealed that ((anchoring filaments~li nk the basement membrane of the epidermis with the deep dermis, in particular in the sinking hnge region. As a result of the higher proliferation of the epidermis with respect to the dermis (heterochrony) and the presence of dermo-epithelial eanchoring filarnents», the superficial laminar epidermis sinks into the dermis to produce new scales. The epidermal downpushing is evidenced by a characteristic distortion of the dermal fibrils under the distal and the proximal sides, and in the hinge region of the forming scales