scholarly journals AN ELECTRON MICROSCOPE STUDY OF THE FINE STRUCTURE OF FEATHER KERATIN

1962 ◽  
Vol 13 (1) ◽  
pp. 1-12 ◽  
Author(s):  
B. K. Filshie ◽  
G. E. Rogers
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Matrix Material ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
Apparent Lack ◽  
Feather Keratin ◽  
Fibrous Protein ◽  
The Matrix ◽  
Lead Hydroxide

Thin sections of the rachis of regenerating follicles of pigmented fowl feathers and of mature non-pigmented seagull feather rachis, embedded in methacrylate and Araldite respectively, were studied in the electron microscope. The late stages of development of keratin fibrils were examined in OsO4-fixed follicle material, and after poststaining with lead hydroxide the keratin aggregates were found to be composed of fine microfibrils approximately 30 A in diameter apparently embedded in a matrix material which had absorbed the lead stain. The centre-to-centre separation of the microfibrils was of the order of 35 A. After bulk treatment by reduction with thioglycollic acid, OsO4 staining, and poststaining with lead hydroxide, a similar microfibrillar fine structure was observed in mature rachis. Only after lead staining could the microfibrils be delineated, and their diameter and separation were similar to that found in the keratin of the follicle. It is suggested that feather keratin resembles α-keratins in consisting of microfibrils embedded in an amorphous protein matrix. However, in comparison with α-keratins, the microfibrils are much smaller in diameter, their arrangement is less orderly, and on the basis of the reactions towards the electron staining procedures, the cystine content of the matrix appears to be not greatly different from that of the microfibrils. The significance of a microfibrillar constitution of feather keratin is discussed in relation to current structural models for this fibrous protein deduced from x-ray diffraction studies. The boundaries between the component cells of feather rachis are desmosomal in character and similar to those of related keratinous structures and a number of different types of cells; the melanin granules are dissimilar to those of mammalian epidermis in their apparent lack of melanin-protein lamellae.

Fine Structure of Interdental Cells in the Mouse Cochlea

1970 ◽  
Vol 28 ◽  
pp. 140-141
Author(s):  
Roberta M. Bruck
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Young Adult ◽  
Uranyl Acetate ◽  
Ground Substance ◽  
Tectorial Membrane ◽  
Lead Citrate ◽  
Unusual Structure ◽  
Thin Sections ◽  
Collagenous Fibers

An unusual structure in the cochlea is the spiral limbus; this periosteal tissue consists of stellate fibroblasts and collagenous fibers embedded in a translucent ground substance. The collagenous fibers are arranged in vertical columns (the auditory teeth of Haschke). Between the auditory teeth are interdental furrows in which the interdental cells are situated. These epithelial cells supposedly secrete the tectorial membrane.The fine structure of interdental cells in the rat was reported by Iurato (1962). Since the mouse appears to be different, a description of the fine structure of mouse interdental cells' is presented. Young adult C57BL/6J mice were perfused intervascularly with 1% paraformaldehyde/ 1.25% glutaraldehyde in .1M phosphate buffer (pH7.2-7.4). Intact cochlea were decalcified in .1M EDTA by the method of Baird (1967), postosmicated, dehydrated, and embedded in Araldite. Thin sections stained with uranyl acetate and lead citrate were examined in a Phillips EM-200 electron microscope.

scholarly journals THE FINE STRUCTURE OF NEURONS

1955 ◽  
Vol 1 (1) ◽  
pp. 69-88 ◽  
Author(s):  
Sanford L. Palay ◽  
George E. Palade
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cerebellar Cortex ◽  
Dorsal Root Ganglia ◽  
Medulla Oblongata ◽  
Dorsal Root ◽  
Thin Sections ◽  
Lipid Inclusions ◽  
Nissl Substance

1. Thin sections of representative neurons from intramural, sympathetic and dorsal root ganglia, medulla oblongata, and cerebellar cortex were studied with the aid of the electron microscope. 2. The Nissl substance of these neurons consists of masses of endoplasmic reticulum showing various degrees of orientation; upon and between the cisternae, tubules, and vesicles of the reticulum lie clusters of punctate granules, 10 to 30 mµ in diameter. 3. A second system of membranes can be distinguished from the endoplasmic reticulum of the Nissl bodies by shallower and more tightly packed cisternae and by absence of granules. Intermediate forms between the two membranous systems have been found. 4. The cytoplasm between Nissl bodies contains numerous mitochondria, rounded lipid inclusions, and fine filaments.

scholarly journals THE CYTOPLASMIC FINE STRUCTURE OF THE DIATOM, NITZSCHIA PALEA

1963 ◽  
Vol 18 (2) ◽  
pp. 429-440 ◽  
Author(s):  
Ryan W. Drum
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Hydrofluoric Acid ◽  
Oil Bodies ◽  
Oil Droplets ◽  
Pennate Diatom ◽  
Thin Sections ◽  
Nitzschia Palea ◽  
Peripheral Cytoplasm

The cytoplasmic fine structure of the motile, pennate diatom, Nitzschia palea was studied in thin sections viewed in the electron microscope. The cells were fixed in OsO4, embedded in methacrylate, and immersed in 10 per cent hydrofluoric acid (HF) for 36 to 40 hours to remove the siliceous cell wall prior to sectioning. The HF treatment did not cause any obvious cytoplasmic damage. The dictyosome complex is perinuclear, and located only in the central cytoplasm. Mitochondria are sparse in the central cytoplasm, but abundant in the peripheral cytoplasm, and fill many of the transvacuolar cytoplasmic strands. Characteristic, amorphous oil bodies fill certain cytoplasmic strands and probably are not leucosin. The pyrenoid appears to be membrane limited, and oil droplets are found adjacent to the pyrenoid. The pyrenoid of another diatom, Cymbella affinis, is also membrane-limited. The membrane limiting the pyrenoid may be a composite of the terminal portions of chloroplast discs, facilitating rapid movement of photosynthate into the pyrenoid matrix, where the characteristic oil droplets may be formed. Carinal fibrils are found singly in each carinal pore, and may be involved in the locomotion of Nitzschia palea.

scholarly journals ТHЕ ANALYSIS OF NATURE OF DAMAGE OF THE MATRIX MATERIAL, USED IN PRODUCTION OF DIAMOND DRILLING AND STONE-WORKING TOOLS DURING THE DESTRUCTION OF A ROCKS

2021 ◽  
Author(s):  
Olena Vynohradova ◽  
◽  
Oleksandr Vasylchuk ◽  
Anatoly Zakora ◽  
Grygorii Petasyuk ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Chemical Composition ◽  
Scanning Electron Microscope ◽  
Diamond Tool ◽  
Roughness Element ◽  
Matrix Material ◽  
Dynamic Interaction ◽  
Short Term ◽  
The Matrix ◽  
Scanning Electron

In this paper are studied themechanism of matrix damage in rock cutting diamond toolswhen interacting with rock. Earlier, in the sludge obtained during mining with a diamond tool on a block of sandstone of the Torez deposit, using a scanning electron microscope (SEM) ZEISS EVO 50 XVP, equipped with Oxford Instruments` Ultim Max 100 energy-dispersive X-ray analyzer (elemental analysis) particles were found whose chemical composition corresponded to the matrix material of the tool. According to the theory of M.V. Kirpichev, the complete correspondence of all configuration elements of the individual studied matrix particles and rock particles, which the sludge obtained as a result of work of diamond tool testifies to a single mechanism of brittle fracture of both counterbodies during dynamic interaction. However, the nature of the matrix material indentation, remains, unexplored. On the basis of the hypothesis that the damage to the matrix material of a diamond tool is carried out by roughness elements from the side of the rock, the goal was set to investigate the wear products of a diamond-free insert made from material, used as a matrix in a diamond rock-breaking tool with a short-term dynamic contact with cooling with a rock block However, the nature of the matrix material indentation, remains, unexplored. The originality of the method lies in the fact that in this study, the destructive indenters are not diamond grains, which gouge out particles of the rock, but elements of the roughness of the rock, which damage theexperimental cylindrical free-diamond element from NiSn (6%), having a density of 7.875 g/cm3, performed by the method of intensive sintering. The sludge obtained as a result of a short-term interaction of the experimental element and the rotating block of the rock on the bench was examined using a , using aabove-mentioned scanning electron microscope. The spectral analysis of the removed from the sludge particle of matrix material from which the experimental diamond-free element was made, confirmed the conformity of chemical composition of particle to the chemical composition of the matrix material of the experimental diamond-free sample.Full correspondence of all configurational components of a NiSn particle (6%) obtained by the action of a rock roughness element on a diamond-free insert during their dynamic interaction with all configurational components of wear particles of a diamond tool matrix., according to the similarity theory of M.V. Kirpichev, confirms the above-mentioned hypothesis.

scholarly journals Cellular invasion into matrix beads: localization of beta 1 integrins and fibronectin to the invadopodia

1991 ◽  
Vol 99 (2) ◽  
pp. 213-225 ◽  
Author(s):  
S.C. Mueller ◽  
W.T. Chen
Keyword(s):  
Cell Surface ◽  
Early Stage ◽  
Matrix Material ◽  
Transformed Cells ◽  
Thin Sections ◽  
Rous Sarcoma ◽  
The Matrix ◽  
Intracellular Compartments ◽  
Beta 1 Integrin ◽  
Cell Invasiveness

We have examined the contribution of adhesion mechanisms to cell invasiveness by growing chicken embryo fibroblasts (CEF) or Rous sarcoma virus-transformed cells (RSVCEF) on fibronectin-coated crosslinked gelatin beads (FN-beads). RSVCEF attached more readily and spread more rapidly on FN-beads than CEF, suggesting an increase in the adhesion-related motility of the transformed cells. In addition, RSVCEF invaded the FN-beads, but CEF did not, by extending specialized cell surface protrusions called invadopodia at sites of cell invasion. FN removal by RSVCEF cultured on prelabeled fluorescent FN-beads (FL-FN) was evident at sites of invadopodia, and internalized FL-FN occurred in vacuoles near the ventral membrane of cells at sites of FN removal. The precise distribution of FN and integrins in cells invading FN-beads was determined by immunofluorescence and immunoelectron microscopy of frozen thin-sections. In both CEF and RSVCEF, beta 1 integrins and FN occupied separate intracellular compartments during the early stage of spreading on FN-beads. Later, beta 1 integrins were largely localized at the ventral cell surface of both CEF and RSVCEF. Polyclonal anti-integrin antibody recognizing beta 1 and several alpha chains, however, labeled both ventral and dorsal cell surfaces. During invasion by RSVCEF, beta 1 integrins were concentrated at extended invadopodia and also colocalized with internalized FL-FN material in phagocytic vesicles. Furthermore, secreted FN was deposited by RSVCEF at the base of invadopodia colocalizing with beta 1 integrin. Both FL-FN matrix removal and formation of the invadopodia were found to be resistant to treatment with GRGDS at concentrations that inhibit the interaction between cells and FN-beads. Thus, the localization of beta 1 integrins to the plasma membrane contacting immobilized FN results in an extremely tight cellular adherence to the matrix bead, that stabilizes invadopodia and also mediates endocytic clearance of degraded FN-matrix material.

Chromocentres and The Synaptinemal Complex

1970 ◽  
Vol 6 (3) ◽  
pp. 655-667
Author(s):  
L. F. LA COUR ◽  
B. WELLS
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
The Other ◽  
Near Surface ◽  
Thin Sections ◽  
Restricted Movement ◽  
Homologous Chromosomes ◽  
Synaptinemal Complex ◽  
Mother Cells ◽  
Fibrillar Network

The 1-4 chromocentres seen in nuclei of Fritillaria lanceolata, which derive from fusion of heterochromatic segments situated proximal to the centromere in all but two of the 24 chromosomes, were studied with the electron microscope in thin sections of pollen mother cells at zygotene and pachytene, in respect of the synaptinemal complex. Prophase stages of meiosis in two plants were also surveyed briefly with the light microscope. The latter observations revealed that the timing of the separation of heterochromatic segments from chromocentres is genetically controlled. In one plant the segments were still contained in chromocentres at pachytene, whereas in the other they were free at zygotene. At this time they could be identified by a near-surface position in the nucleus and an even condensation concomitant with an absence of chromomeres. In thin section, the fine structure of the chromocentres in zygotene nuclei was distinctive in that the chromatin fibrils were less condensed and more widely dispersed than those in euchromatic regions. The fibrillar network was also interspersed with ‘clear areas’ or channels. After further chromosome condensation, the condensation of fibrils in the chromocentres became equivalent at pachytene to those in euchromatic regions. Synaptinemal complexes were seen at zygotene and pachytene both in euchromatic regions and chromocentres. Their presence in the chromocentres signifies that homologous chromosomes must have been closely paired in regions extending from the centromeres to the distal ends of the heterochromatic segments already at telophase of the last pre-meiotic mitosis. Configurations involving entangled pairs of axial cores, peculiar to zygotene and chromocentres and parts of euchromatic regions proximal to them, are interpreted as resulting from restricted movement.

AN ELECTRON MICROSCOPE STUDY OF THIN SECTIONS OF HAEMOPHILUS VAGINALIS (GARDNER AND DUKES) AND SOME POSSIBLY RELATED SPECIES

1966 ◽  
Vol 12 (6) ◽  
pp. 1125-1136 ◽  
Author(s):  
Alice Reyn ◽  
A. Birch-Andersen ◽  
S. P. Lapage
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Lactobacillus Acidophilus ◽  
Related Species ◽  
Electron Microscope Study ◽  
Similar Degree ◽  
Gram Positive ◽  
Thin Sections

The line structure of Haemophilus vaginalis (Gardner and Dukes 1955) was compared with that of four, possibly related species (Butyribacterium rettgeri, Corynebacterium diphtheriae var. mitis, Lactobacillus acidophilus, Haemophilus influenzae) and an unrelated species, Neisseria haemolysans, which had shown a similar degree of Gram-variability as that of H. vaginalis. Although H. vaginalis was first described as a Gram-negative rod, its fine structure, particularly that of cell wall and septa, was more like that of Gram-positive organisms. Also N. haemolysans had a fine structure close to that of Gram-positive organisms, and its typical Gram-positive cell wall varied in. thickness from one cell to another.The study did not solve the problem of the classification of the so-called H. vaginalis, but the appearance of the few strains studied in the electron microscope suggests that it: should be included in Corynebacterium or Butyribacterium rather than in Lactobacillus.

The fine structure and development of chlamydospores of Fusarium oxysporum

1972 ◽  
Vol 18 (7) ◽  
pp. 997-1002 ◽  
Author(s):  
I. L. Stevenson ◽  
S. A. W. E. Becker
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cell Surface ◽  
Outer Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Hyphal Wall

Methods have been developed for the rapid, reproducible induction of high-density populations of F. oxysporum chlamydospores. On transferring washed pregerminated conidia to a simple two-salts medium, chlamydospore morphogenesis was evident by 12 h and masses of mature spores could be harvested at the end of 4 days. Electron-microscope studies of thin sections of mature chlamydospores reveal a thick triple-layered cell wall. The cytoplasm contains, in addition to large lipid deposits, a nucleus, mitochondria, and endoplasmic reticulum all typical of fungal cells. Chlamydospores of F. oxysporum exhibit two distinct types of cell surface in thin section. The outer wall layer of two of the isolates studied was smooth-surfaced while the outer layer of the two other isolates was distinctly fibrillose. Some evidence is presented suggesting that the fibrillose material arises through the partial breakdown of the original hyphal wall.

The equivalence of electron-microscope and X-ray observations on collagen fibres

1955 ◽  
Vol 233 (1192) ◽  
pp. 1-16 ◽  
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Density Fluctuations ◽  
Density Functions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Biological Interest ◽  
Wide Range ◽  
Tail Tendon ◽  
Rat Tail

One of the outstanding properties of collagen fibrils is an axial periodicity of about 640 Å and associated fine structure which can be observed directly in the electron microscope and also may be deduced from observation of low-angle X-ray diffraction. This paper gives first an account of measurements of density fluctuations along the fibril axis for unstained, unshadowed fibrils for one mammalian collagen, rat-tail tendon, and one avian collagen, fowl-neck tendon. The main and subsequent part of the paper shows how the density functions derived from electron micrographs obtained under specified conditions may be used to calculate the intensities of low-angle X-ray diffraction. Complications arise from the fact—of considerable biological interest—that for any one material a wide range of fine structure exists. For this reason it has been necessary to introduce a modulating function to represent the behaviour of a system of fibrils with differing density functions. The calculated structure amplitudes are compared with those measured from low-angle X-ray photographs of dry fibres. Good agreement between the two sets of results is found for rat-tail tendon and fair agreement for fowl-neck tendon. The agreement for fowl-neck tendon is improved by the application of a more general modulating function.

scholarly journals THE FINE STRUCTURE OF THE MID-BODY OF THE RAT ERYTHROBLAST

1962 ◽  
Vol 13 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Robert C. Buck ◽  
James M. Tisdale
Keyword(s):  
Bone Marrow ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cleavage Furrow ◽  
Intercellular Bridge ◽  
Spindle Fiber ◽  
Thin Sections ◽  
Rat Bone ◽  
Spindle Fibers

The development of the mid-body has been studied in mitotic erythroblasts of the rat bone marrow by means of thin sections examined with the electron microscope. A differentiated region on the continuous spindle fibers, consisting of a localized increase in density, is observed at the equatorial plane. The mid-body seems to develop by the aggregation of such denser lengths of spindle fiber. Its appearance precedes that of the cleavage furrow. A plate-like arrangement of fibrillary material lies transversely across the telophase intercellular bridge. Later, this material becomes amorphous and assumes the form of a dense ring closely applied to a ridge in the plasma membrane encircling the middle of the bridge. Although the mid-body forms in association with the spindle fibers, it is a structurally distinct part, and the changes which it undergoes are not shared by the rest of the bundle of continuous fibers.

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