The nature of reaction wood. VI. The reaction anatomy of seedlings of woody perennials.

1962 ◽  
Vol 10 (2) ◽  
pp. 93 ◽  
Author(s):  
G Scurfield ◽  
AB Wardrop
Keyword(s):  
Fibre Length ◽  
Structural Features ◽  
Age Difference ◽  
Reaction Wood ◽  
Lower Side ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Gelatinous Layer ◽  
Ray Cells ◽  
Electron Microscopes

The reaction anatomy of the stems of seedlings of A 1 species of hroad-leaved trees was examined. The reaction was induced by bending the stems at right angles or growing the plants horizontally. As a result of greater cambial activity on the upper side such stems developed a structural asymmetry characterized by enhanced xylem and phloem development. The structural features of the lower side were similar to those of stems grown vertically. The xylem on the upper side contained fewer vessels, more fibres, and fewer medullary rays than that on the lower side of the same stem. "Gelatinous" layers developed within the reaction fibres as well as in fibres of the phloem. Vessels, medullary ray cells, and parenchyma cells were often compressed and sometimes obliterated. Reaction fibres showed reduced wall pitting and tended to retain their contents until they lay relatively deep within the stem. There were no differences in fibre length between upper and lower sides of the stem, but comparisons were probably confounded with an age difference. Cortical cells and, in species where they occurred, canals were compressed on that side of the stem. Such cortical cells were not only smaller in cross section than those on the lower side, but were also shorter in length. This was also a feature of medullary ray cells. There was a greater accumulation of tannins in phloem and cortex on the upper side of the stem. The structure of reaction fibres was examined in ultraviolet, polarizing, and electron microscopes. In the first of these, the "gelatinous" layer was seen to consist of a series of concentric bands convoluted towards the cell lumen, the bands containing radial striations. The polarizing microscope showed that the innermost part of the wall possessed some birefringence. Both convolutions and birefringence tended to disappear as the cells matured; staining with Congo red became less intense. The heterogeneity of the "gelatinous" layer was confirmed by electron microscopic examination. The results are discussed in connection with the gravimorphic responses of displaced stems, the altered patterns of lignification, and the development of growth stresses in such stems.

The nature of reaction wood. IV. Variations in cell wall organization of tension wood fibres

1955 ◽  
Vol 3 (2) ◽  
pp. 177 ◽  
Author(s):  
AB Wardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Wall ◽  
Degree Of Crystallinity ◽  
Tropical Species ◽  
Normal Wood ◽  
Reaction Wood ◽  
Gelatinous Layer ◽  
Wood Fibres ◽  
Cell Wall Organization

The cell wall organization, the cell wall texture, and the degree of lignification of tension wood fibres have been investigated in a wide variety of temperate and tropical species. Following earlier work describing the cell wall structure of tension wood fibres, two additional types of cell wall organization have been observed. In one of these, the inner thick "gelatinous" layer which is typical of tension wood fibres exists in addition to the normal three-layered structure of the secondary wall; in the other only the outer layer of the secondary wall and the thick gelatinous layer are present. In all the tension wood examined the micellar orientation in the inner gelatinous layer has been shown to be nearly axial and the cellulose of this layer found to be in a highly crystalline state. A general argument is presented as to the meaning of differences in the degree, of crystallinity of cellulose. The high degree of crystallinity of cellulose in tension wood as compared with normal wood is attributed to a greater degree of lateral order in the crystalline regions of tension wood, whereas the paracrystalline phase is similar in both cases. The degree of lignification in tension wood fibres has been shown to be extremely variable. However, where the degree of tension wood development is marked as revealed by the thickness of the gelatinous layer the lack of lignification is also most marked. Severity of tension wood formation and lack of lignification have also been correlated with the incidence of irreversible collapse in tension wood. Such collapse can occur even when no whole fibres are present, e.g. in thin cross sections. Microscopic examination of collapsed samples of tension wood has led to the conclusion that the appearance of collapse in specimens containing tendon wood can often be attributed in part to excessive shrinkage associated with the development of fissures between cells, although true collapse does also occur. Possible explanations of the irreversible shrinkage and collapse of tension wood fibres are advanced.

scholarly journals The Fine Structure of Synapses in the Ciliary Ganglion of the Chick

1960 ◽  
Vol 7 (1) ◽  
pp. 31-36 ◽  
Author(s):  
A. J. de Lorenzo
Keyword(s):  
Fine Structure ◽  
Synaptic Vesicles ◽  
Ganglion Cells ◽  
Single Cells ◽  
Synaptic Cleft ◽  
Structural Features ◽  
Ciliary Ganglion ◽  
Single Axon ◽  
Electron Microscopes ◽  
Electron Microscope Image

Ciliary ganglia of chick embryos and newly hatched chicks were examined in the light and electron microscopes. Particular attention was given to the fine structure of calyciform synapses, which are characteristically found in ciliary ganglia of birds. The calyciform endings are characterized by large expansions of the presynaptic axons upon ganglion cells, and the terminal processes extend over a considerable area of the cell surface. Often, indeed they appear to envelop the cell. In the electron microscope image, the appositional membranes are separated by a space about 300 to 400 A wide; i.e., the synaptic cleft. At irregularly spaced regions, the appositional membranes show areas of increased density. The presynaptic processes contain clusters of synaptic vesicles, localized at these dense regions. Thus the fine structure complex typical of other synapses is evident. The unique structural features of this synapse are as follows: (a) The calyx or presynaptic terminal derives from a single axon, does not arborize, and terminates upon a single ganglion cell. Thus, unlike the classical bouton terminal, this represents an anatomical device for firing single cells by single axons. (b) The surface area in contiguity, i.e., the area of appositional membranes, is far more extensive than the bouton terminal. The fine structure of this synapse is compared with others, for example, the classical boutons terminaux and purely electrical synapses, in an attempt to correlate fine structure with function.

Anatomical Characteristics and Ecological Trends in the Xylem and Phloem of Brassicaceae and Resedacae

IAWA Journal ◽  
2006 ◽  
Vol 27 (4) ◽  
pp. 419-442 ◽  
Author(s):  
Fritz Hans Schweingruber
Keyword(s):  
Western Europe ◽  
Life Forms ◽  
Reaction Wood ◽  
Lower Altitude ◽  
Alpine Zone ◽  
Brassicaceae Species ◽  
Ray Cells ◽  
The Alps ◽  
The Hill ◽  
Vestured Pits

The xylem and phloem of Brassicaceae (116 and 82 species respectively) and the xylem of Resedaceae (8 species) from arid, subtropical and temperate regions in Western Europe and North America is described and analysed, compared with taxonomic classifications, and assigned to their ecological range. The xylem of different life forms (herbaceous plants, dwarf shrubs and shrubs) of both families consists of libriform fibres and short, narrow vessels that are 20–50 μm in diameter and have alternate vestured pits and simple perforations. The axial parenchyma is paratracheal and, in most species, the ray cells are exclusively upright or square. Very few Brassicaceae species have helical thickening on the vessel walls, and crystals in fibres. The xylem anatomy of Resedaceae is in general very similar to that of the Brassicaceae. Vestured pits occur only in one species of Resedaceae.Brassicaceae show clear ecological trends: annual rings are usually distinct, except in arid and subtropical lowland zones; semi-ring-porosity decreases from the alpine zone to the hill zone at lower altitude. Plants with numerous narrow vessels are mainly found in the alpine zone. Xylem without rays is mainly present in plants growing in the Alps, both at low and high altitudes. The reaction wood of the Brassicaceae consists primarily of thick-walled fibres, whereas that of the Resedaceae contains gelatinous fibres. The frequency of sclereids in Brassicaceae bark is an indicator of ecological differences: sclereids are rare in plants from the alpine zone and frequent in plants from all other ecotones.

Features of the architectonics of the microstructure of the primary remex of Owls (Strigiformes) due to the specifics of the flight

2021 ◽  
Vol 66 (2) ◽  
pp. 232-246
Author(s):  
E. O. Fadeeva
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cross Section ◽  
Dorsal Surface ◽  
Structural Features ◽  
Electron Microscopic Investigation ◽  
Original Research ◽  
Electron Microscopic ◽  
Microstructural Characteristics ◽  
Scanning Electron

Conducted electron microscopic investigation of the primary remex fine structure of thirteen species of Owls (Strigiformes), using a scanning electron microscope (SEM). It is shown that Owls (Strigiformes) have a number of specific primary remex microstructural characteristics. First of all, these are the features of the structure of the pennaceous barb: a cross section configuration, a pith architectonics on the cross section and longitudinal sections, a cuticular structur of the barb. A number of the unique features in the microstructure of the vanules of the pennaceous barb have been found for the first time (at the scanning electron microscope level, at a large SEM magnification). First of all, these are the structural features of the distal barbules and the structure of the apical portion of the barb with the elongated proximal barbules and the distal barbules tightly contiguous to the ramus and closed with each other. Mentioned characteristics make for the thick velvet-like dorsal surface of the vane and the presence of a complex of peculiar “bunches” (fringes) forming the cleft edge (a fringed edge) of the inner vane – exceptionally specific adaptive characteristics in Strigiformes. Рresentenced original research results suggest that Owls (Strigiformes) have a number specific microstructural characteristics of the primary remex and also a number of the unique features in the microstructure of the primary remex which reflecting the ecological and morphological adaptations conditioned by the flight specificity.

The nuclear pore complex: three-dimensional surface structure revealed by field emission, in-lens scanning electron microscopy, with underlying structure uncovered by proteolysis

1993 ◽  
Vol 106 (1) ◽  
pp. 261-274 ◽  
Author(s):  
M.W. Goldberg ◽  
T.D. Allen
Keyword(s):  
Nuclear Pore Complex ◽  
Three Dimensional ◽  
Underlying Structure ◽  
Nuclear Pore ◽  
Electron Microscopic ◽  
Biologically Relevant ◽  
Fine Grained ◽  
Outer Periphery ◽  
Electron Microscopes ◽  
Scanning Electron

The structure of the nuclear pore complex (NPC) has been previously studied by many different electron microscopic techniques. Recently, scanning electron microscopes have been developed that can visualise biologically relevant structural detail at the same level of resolution as transmission electron microscopes and have been used to study NPC structure. We have used such an instrument to visualise directly the structure of both cytoplasmic and nucleoplasmic surfaces of the NPC of manually isolated amphibian oocyte nuclear envelopes that have been spread, fixed, critical point dried and coated with a thin fine-grained film of chromium or tantalum. We present images that directly show features of the NPC that are visible at each surface, including coaxial rings, cytoplasmic particles, plug/spoke complexes and the nucleoplasmic basket or fishtrap. Some cytoplasmic particles are rod-shaped or possibly “T”-shaped, can be quite long structures extending into the cytoplasm and may be joined to the coaxial ring at a position between each subunit. Both coaxial rings, which are proud of the membranes, can be exposed by light proteolytic digestion, revealing eight equal subunits each of which may be bipartite. We have determined that the nucleoplasmic filaments that make up the baskets are attached to the outer periphery of the coaxial ring at a position between each of its subunits. These filaments extend into the nucleoplasm and insert at the distal end to the smaller basket ring. The space left between adjacent basket filaments would exclude particles bigger than about 25 nm, which is consistent with the exclusion limit previously found for NPC-transported molecules.

Electron microscopic studies on the structure of motile primordial germ cells of Xenopus laevis in vitro

Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 119-133
Author(s):  
Janet Heasman ◽  
C. C. Wylie
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Structural Features ◽  
Culture Conditions ◽  
Structural Basis ◽  
Electron Microscopic ◽  
Microscopic Studies

Primordial germ cells (PGCs) of Xenopus laevis have been isolated from early embryos and kept alive in vitro, in order to study the structural basis of their motility, using the transmission and scanning electron microscope. The culture conditions used mimicked as closely as possible the in vivo environment of migrating PGCs, in that isolated PGCs were seeded onto monolayers of amphibian mesentery cells. In these conditions we have demonstrated that: (a) No significant differences were found between the morphology of PGCs in vitro and in vivo. (b) Structural features involved in PGC movement in vitro include (i) the presence of a filamentous substructure, (ii) filopodial and blunt cell processes, (iii) cell surface specializations. These features are also characteristic of migratory PGCs studied in vivo. (c) PGCs in vitro have powers of invasion similar to those of migrating PGCs in vivo. They occasionally become completely surrounded by cells of the monolayer and, in this situation, bear striking resemblance to PGCs moving between mesentery cells to the site of the developing gonad in stage-44 tadpoles. We conclude that as far as it is possible to assess, the behaviour of isolated PGCs in these in vitro conditions mimics their activities in vivo. This allows us to study the ultrastructural basis of their migration.

ANATOMY AND CHEMICAL COMPOSITION OF LIRIODENDRON TULIPIFERA STEMS INCLINED AT DIFFERENT ANGLES

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 463-475 ◽  
Author(s):  
Tokiko Hiraiwa ◽  
Haruna Aiso ◽  
Futoshi Ishiguri ◽  
Yuya Takashima ◽  
Kazuya Iizuka ◽  
...  
Keyword(s):  
Lignin Content ◽  
Fibre Length ◽  
Liriodendron Tulipifera ◽  
Original Position ◽  
Chemical Characteristics ◽  
Normal Wood ◽  
Reaction Wood ◽  
Glucose Content ◽  
Wood Fibres ◽  
S2 Layer

The anatomical and chemical characteristics of reaction wood (RW) were investigated in Liriodendron tulipifera Linn. Stems of seedlings were artificially inclined at angles of 30 (RW-30), 50 (RW-50) and 70° (RW-70) from the vertical, and compared with normal wood (NW) from a vertical seedling stem. The smallest values for the wood fibre length and vessel number were observed in RW-50. The pit aperture angle was less than 10° in RW-30 and RW-50, in which reduced lignin content was observed in the S2 layer of the wood fibres. An increase in the glucose content and a decrease in the lignin and xylose content was observed in RW-50. The stem inclination angle affected the degree of RW development with regard to anatomical and chemical characteristics: the severest RW was observed in RW-50, followed by RW-30. RW-70 was similar in anatomical and chemical characteristics to NW, apparently because the inclination was too strong to enable recovery of its original position. In this case a vertical sprouting stem was formed to replace the inclined stem.

scholarly journals Electron Microscopic Observations on Spinal Ganglion Cells of Rana pipiens after Injection of Malononitrile

1958 ◽  
Vol 4 (1) ◽  
pp. 83-86 ◽  
Author(s):  
Everett Anderson ◽  
V. L. van Breemen
Keyword(s):  
Golgi Complex ◽  
Rana Pipiens ◽  
Ganglion Cells ◽  
Morphological Changes ◽  
Membrane System ◽  
Spinal Ganglion ◽  
Electron Microscopic ◽  
Biochemical Alterations ◽  
Spinal Ganglion Cells ◽  
Electron Microscopes

Spinal ganglionic cells of Rana pipiens were studied with light and electron microscopes in normal animals and in animals which had received graded dosages of malononitrile intraperitoneally. After treatment no increase in the intensity of staining was noted in the Nissl substance when spinal ganglion cells were examined with the light microscope. The electron micrographs demonstrated the following in malononitrile-treated animals: 1. The cisternae of the endoplasmic reticulum composing the Nissl bodies appeared to fragment and lose their parallel orientation. 2. The microvesicular components of the Golgi complex appeared to increase in number, and the increase was apparently due to fragmentation of the membrane system of the Golgi complex. 3. The mitochondria enlarged and became pleomorphic, but displayed no alterations of internal structure. The morphological changes may be interpreted as reflections of biochemical alterations.

Correlated 3D Light and Electron Microscopy of Large, Complex Structures: Analysis of Transverse Tubules in Heart Failure

1998 ◽  
Vol 4 (S2) ◽  
pp. 440-441
Author(s):  
Maryann E. Martone ◽  
Andrea Thor ◽  
Stephen J. Young ◽  
Mark H. Ellisman.
Keyword(s):  
Electron Microscopy ◽  
Electron Tomography ◽  
Light And Electron Microscopy ◽  
Structural Features ◽  
Electron Microscopic Level ◽  
Specimen Preparation ◽  
Large Sample Size ◽  
Electron Microscopic ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron

Light microscopic imaging has experienced a renaissance in the past decade or so, as new techniques for high resolution 3D light microscopy have become readily available. Light microscopic (LM) analysis of cellular details is desirable in many cases because of the flexibility of staining protocols, the ease of specimen preparation and the relatively large sample size that can be obtained compared to electron microscopic (EM) analysis. Despite these advantages, many light microscopic investigations require additional analysis at the electron microscopic level to resolve fine structural features.High voltage electron microscopy allows the use of relatively thick sections compared to conventional EM and provides the basis for excellent new methods to bridge the gap between microanatomical details revealed by LM and EM methods. When combined with electron tomography, investigators can derive accurate 3D data from these thicker specimens. Through the use of correlated light and electron microscopy, 3D reconstructions of large cellular or subcellular structures can be obtained with the confocal microscope,

Anatomy and ultrastructure of a Rhododendron root–fungus association

1980 ◽  
Vol 58 (23) ◽  
pp. 2421-2433 ◽  
Author(s):  
T. A. Peterson ◽  
W. C. Mueller ◽  
L. Englander
Keyword(s):  
Fungal Infection ◽  
Secondary Growth ◽  
Cortical Layer ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Host Cytoplasm ◽  
Hair Roots ◽  
Short Period ◽  
Infected Cells ◽  
Hyphal Coils

Light and electron microscopic investigations of the roots of Rhododendron and other ericaceous plants growing in the vicinity of Clavaria fruiting structures showed a fungal infection consistently associated with the epidermal and cortical cells of the "hair roots." Uninfected hair roots consisted of an epidermis and a one cell thick cortical layer surrounding the stele. Secondary growth in the stele and formation of a cork layer by division of the pericycle caused the cortex and epidermis to slough as the root matured. The structure of the infected hair roots was similar except for the presence of fungus in epidermal and cortical cells. As judged by the appearance of septa, at least two fungi were involved, one with dolipore septa that formed hyphal coils in the infected cells, and one with septa associated with Woronin bodies that occurred as single hyphal strands. Hyphae were found penetrating the cells from the exterior of the root and also passing from cell to cell. No correlation between fungal infection and the phenolic content of the cells could be made. Dissolution of both the fungal and host cytoplasm appeared to occur as the cells were sloughed. It appears that the fungus–root relationship is complex and is limited in duration to a short period of time during the development of the hair roots.

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