41 research outputs found
COLLAGEN FIBRIL ULTRASTRUCTURE ALTERS AFTER GLYCANOLYTIC DIGESTION
No full textFixed fragments of bovine nasal septum cartilage were digested for six hours either with testicular hyaluronidase or streptomyces hyaluronidase or flavobacter chondroitinase ABC, and observed with a transmission electron microscope. Collagen fibril diameters (D) were measured to evaluate the effect of enzymatic digestion on the fibril size. This resulted in an increased frequency (17 % to 47 %) of "thin" fibrils (80 to 32 nm), followed by a decrease (65 % to 31 %) of the frequency of "mid" fibrils (32 to 64 nm). The frequency of "thick" fibrils (over 64 nm) showed a moderate increase (18 % to 22 %). Considering the relationship between fibril diameter, fibril volume and collagen content, the apparently relevant increase in number of the "thin" fibrils corresponds to an alteration of only 4 % of the total collagen. On the other hand the increase of the "thick" fibrils implies a conspicuous alteration of 20 % of the total collagen. The observed fibril rearrangement after digestion may be explained in terms of the wrap of matrix proteoglycans around each fibril. The enzymatic removal of the proteoglycans could make "mid" collagen fibrils free to regress into "thin" as well as to merge together into "thick" fibrils
Morphology of epiphyseal apparatus of a ranid frog (Rana Esculenta)
No full textMorphological, histochemical and ultrastructural investigations on epiphyseal apparatus of Rana Esculenta were made. The most important findings were the following: 1) metaphyseal cartilage is localized inside proximal diaphyseal compact bone as a plug; 2) metaphyseal cartilage do not reduce in thickness during ageing; 3) metaphyseal cartilage do not show vascular invasion and do not mineralize in degenerative zone; 4) trabecular bone was not at all evident in this animal; 5) external periosteum is well vascularized and proliferates in correspondence to marginal epiphyseal end of the diaphyseal. From these results the hypothesis that the ranid frog bone growth is not due to metaphyseal metabolism (as in avian and mammals) but to bone periosteal marginal mineralization is reached
Ca++ and Na+ , K+ ATPase activities in the fungiform papilla of the tongue of rana esculenta (Anura Ranidae).
No full textSTRUCTURES RECOGNITION IN ATOMIC FORCE MICROSCOPY: PRE- AND POST-PROCESSING TECHNIQUES.
No full textItalian Journal of Anatomy and Embryology 105 Suppl.1 Fasc.2, 192, 200
The dependency of collagen fibrillogenesis in vitro on fibroblasts culture conditions. Fibroblasts in mono- and multi- layers
No full textThe extracellular matrix produced by monolayer and tridimensional cultures of fibroblasts was investigated using histochemical and ultrastructural methods. In monolayer cultures, collagen and proteoglycans produced by fibroblasts could not be organized into morphologically recognizable structures. Tridimensional fibroblast cultures produced a well organized matrix with periodic, parallel ordered collagen fibrils of 50 nm diameter, criss-crossed by alcianophylic segments 6-10 nm thick in diameter and 100-300 nm in length, parallel to each other, perpendicular to the collagen fibrils and spaced 67 nm from each other. Some alcianophylic segments lay perpendicular to the above described ones, with maximum lengths of 65-70 nm. Alcianophylic segments are the ultrastructural evidence of structural proteoglycans. These observations suggest that the culture conditions influence the collagen and proteoglycans secretion, so that the final organization of the matrix results quite different
Chemical etching in processing cortical bone specimens for scanning electron microscopy
No full textTransverse and longitudinal sectioning of undecalcified cortical bone is a commonly employed technique for investigating the lamellar structure of the osteons. Since a flat surface is required, the specimen has to be grinded and then polished. Whereas the smear of debris and inorganic/organic deposits left by these treatments cannot be removed by ultrasonication alone, a chemical treatment of the specimen surface with either a basic or an acid etching solution is currently employed. A further effect of the latter can be the enhancement of the lamellar bone pattern. The kind of etching solution, its pH, the concentration of etchants, and the contact time significantly affect the sectioned surface when it is observed with scanning electron microscopy (SEM). The etching procedures can severely influence the obtained images. Homogeneous cortical bone specimens were sampled from the first metatarsal of two fresh human subjects. One or two cut surfaces were exposed to different acid and basic solutions in bonded conditions. Considering the type of chemical agents, the solution pH, and the exposure time of the specimens, the effects of several etching media have been investigated and compared. Strong etching, either acid or basic produced surface decalcification and severe damage of the collagen matrix, compromising any morphological or morphometric analysis. Weak acid etching (for example citric and acetic acid), even though causing distinctive alteration of the sample, enhanced the visibility of the lamellar pattern, while the polyphosphate treatment of the surface decalcified a thin layer matrix, ensuring a good visibility of fibrils and avoiding rough distortions
Recognition of cell surface modulation by elliptic Fourier analysis.
No full textA development of elliptic Fourier analysis, consisting in an alignment of harmonics according to their clockwise or counter-clockwise rotation, resolves the discrepancy between calculated harmonic frequencies and observed morphological periodicities. The new technique is supported by consistent data of empiric and fractal contours, comparatively analyzed and visualized with and without harmonic alignment. The method is particularly suitable for the recognition of periodic modulations of the cell surface. A preliminary analysis of two different cell populations (echinocytes and chondrocytes) shows distinct patterns of surface modulation that allow an effective discrimination of the cell type, while providing relevant information about the respective cytological configurations
