scholarly journals The Fine Structure of Endothelium of Large Arteries

1958 ◽  
Vol 4 (2) ◽  
pp. 187-190 ◽  
Author(s):  
R. C. Buck
Keyword(s):  
Endothelial Cells ◽  
Fine Structure ◽  
Electron Microscope ◽  
Double Row ◽  
Thorium Dioxide ◽  
Thin Sections ◽  
Large Arteries ◽  
Arterial Lumen ◽  
Characteristic Features ◽  
Silver Granules

Endothelium of large arteries from several species was studied in thin sections with the electron microscope. Before sacrifice, some animals received an intravenous injection of colloidal thorium dioxide which was visualized in the sections. Surface replicas were prepared by carbon evaporation on either frozen-dried endothelium or on endothelium dried by sublimation of naphthalene with which the tissue had been impregnated. Cell boundaries, stained with silver, were observed in sections and also from the surface by stripping off the inner part of the endothelium. In addition to the usual cytoplasmic organelles, the endothelial cells showed certain characteristic features, namely, large invaginated pockets communicating with the arterial lumen, numerous much smaller vesicular structures immediately under the plasma membrane and apparently also communicating with the lumen, and inclusions, into which injected thorium particles were incorporated. Intercellular boundaries appeared as regular double membranes in thin sections, and they were outlined by a double row of silver granules after silver staining. No evidence was obtained of permeation of intracellular spaces by colloidal thorium.

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 Structure of the Rete Mirabile in the Kidney of the Rat as Seen with the Electron Microscope

1960 ◽  
Vol 7 (1) ◽  
pp. 103-106 ◽  
Author(s):  
J. B. Longley ◽  
W. G. Banfield ◽  
D. C. Brindley
Keyword(s):  
Endothelial Cells ◽  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Simple Diffusion ◽  
Functional Capabilities ◽  
Rete Mirabile ◽  
Peritubular Capillaries ◽  
Fenestrated Endothelium

Electron micrographs of the rete mirabile in the medulla of the rat have revealed that the endothelium of the afferent and efferent vessels are markedly different in fine structure. The venous capillaries returning blood from the papilla are lined with a fenestrated endothelium much like that in the peritubular capillaries of the kidney. The arterial capillaries delivering blood to the papilla have an unperforated lining of overlapping endothelial cells with extremely irregular tapered margins. It is pointed out that the organization of particularly the latter vessels suggests that the functional capabilities of these retia go beyond those of a simple diffusion countercurrent exchanger.

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.

Cell Border Demarcation in the Scanning Electron Microscope by Silver Stains

1974 ◽  
Vol 16 (1) ◽  
pp. 221-239
Author(s):  
W. C. DE BRUIJN ◽  
W. VAN MOURIK ◽  
I. J. BOSVELD
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cell Surface ◽  
Silver Nitrate ◽  
Aortic Tissue ◽  
Cell Border ◽  
Thorium Dioxide ◽  
Dextran Solution ◽  
Scanning Electron

Silver nitrate and silver proteinate were both successfully used as electron stains for the demarcation of the aortic endothelial cell borders in the scanning electron microscope. By energy-dispersive X-ray analysis it was demonstrated that silver was present in the demarcation lines around the endothelial cells. The presence of silver closely coincided with the places where secondary electrons were produced. Judged by the quality of the aortic tissue in the transmission electron microscope, the method using silver proteinate was preferable to those using silver nitrate. The limited resolution of the method is demonstrated. The role of the dextran solution in such procedures was investigated, and it was shown that the presence of such a dextran solution, or its particle size or charge, does not contribute to the formation of these silver lines around the endothelial cells. In ultrathin sections of such material the cell surface-contrasting capacity of colloidal thorium dioxide solutions was compared to the cell border-contrasting capacity of silver proteinate. It was found that prior aldehyde fixation abolished the cell border demarcation by silver proteinate, but only reduced the cell surface demarcation by thorium dioxide particles.

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.

scholarly journals TRANSPORT OF GLOBIN BY THE RENAL GLOMERULUS

1964 ◽  
Vol 120 (6) ◽  
pp. 1129-1138 ◽  
Author(s):  
Max G. Menefee ◽  
C. Barber Mueller ◽  
Allen L. Bell ◽  
Joseph K. Myers
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Basement Membranes ◽  
Renal Glomerulus ◽  
Thin Sections ◽  
Characteristic Appearance ◽  
Pass Through ◽  
Surrounding Membrane ◽  
Glomerular Capillaries

Purified human globin injected into rats forms aggregates which are identifiable by their characteristic appearance in thin sections in the electron microscope and by their positive autoradiographs when the globin is tritiated before injection. Globin is taken up by endothelial cells of glomerular capillaries and is transported across the cell within the limits of a surrounding membrane. Globin is rarely seen to pass through fenestrations. Globin is also taken into the stalk region where it is seen usually within the sponge fibers and only occasionally within stalk cells. Globin is seen in all stages of passage through the basement membranes and sponge fibers, which are not deformed by its passage. On the basis of the findings presented here and by others, it is postulated that the basement membrane and sponge fibers consist of a thixotrophic gel. After traversing the basement membrane, the globin passes between foot processes of the epithelial cells. The slit membranes are deformed by this passage and thus appear to be distinctive structures. The globin is next found free in Bowman's space; the earliest aggregates are seen there within 1 minute after injection. Globin taken up in the stalk region is slowly discharged and very little is found there 6 hours postinjection.

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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