Wound Reaction of the Parenchyma in Betula

IAWA Journal ◽  
1990 ◽  
Vol 11 (4) ◽  
pp. 413-420 ◽  
Author(s):  
Uwe Schmitt ◽  
Walter Liese
Keyword(s):  
Betula Pendula ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Protective Layer ◽  
Xylem Parenchyma ◽  
Fibrillar Material ◽  
Pit Membrane ◽  
Wound Reaction ◽  
Simultaneous Loss ◽  
Perforation Plates

Reactions in the xylem parenchyma of Betula pendula Roth following wounding in late spring have been investigated by light and electron microscopy. Structural changes in contact parenchyma cells are described in relation to the formation of plugs in vessels and fibres. Swelling of the Protective Layer (PL) with a simultaneous loss in electron density appears first. Fibrillar material is then synthesised, which accumulates outside the cytoplasm between the plasmalemma and the modified PL. The PL now consists of loosely packed fibrils with a structure similar to the accumulating fibrillar material. After extrusion of fibrils through the pit membrane into the lumina of adjacent vessels a membranous layer on the scalariform perforation plates as well as plugs are formed; the latter are also built up in fibres. These reactions spread axially less extensively in cells near the cambium than in the more centrally located ones.

An Ultrastructural and Radio-Autographic Study of the Evolution of the Interphase Nucleus in Plant Meristematic Cells (Allium Porrum)

1974 ◽  
Vol 14 (2) ◽  
pp. 263-287
Author(s):  
J. G. LAFONTAINE ◽  
A. LORD
Keyword(s):  
Interphase Nucleus ◽  
Structural Changes ◽  
Tritiated Thymidine ◽  
Light And Electron Microscopy ◽  
Allium Porrum ◽  
Meristematic Cells ◽  
Fibrillar Material ◽  
Nuclear Structures ◽  
S Period ◽  
Dense Chromatin

Radioautography under both light and electron microscopy was exploited to investigate the structural changes of the chromatin reticulum which characterizes the interphase nucleus of a number of plants. Allium porrum meristematic plant cells were used for this purpose. In this species, the telophase chromosomes uncoil into dense strands which, during the G1 period, gradually give rise to a coarse reticulum. There then follows an extensive unravelling of portions of these strands, and high-resolution radioautography reveals that labelling with tritiated thymidine predominantly occurs over zones of the nucleus consisting of diffuse fine fibrillar material. As the S-period progresses, a chromatin reticulum reappears throughout the nuclear cavity, the tortuous strands being approximately 0.25 µm in diameter. Most of the radioautographic grains still remain over the light nucleoplasmic areas but a number of these are now located on the outermost portion of the dense chromatin profiles. By the end of the S-period, the chromatin strands are slightly thicker (ca. 0.3 µm) and form a looser reticulum. Labelling has decreased noticeably in nuclei of that period, the radioautographic grains being grouped into clusters resting over more or less spherical regions of the chromatin reticulum. Judging from their localization at the surface of the nucleolus or close to the nuclear envelope, these structures correspond to chromocentres. The additional interesting finding that such nuclear structures appear much less compactly organized strongly suggests that chromocentres undergo important conformational modifications during duplication of their DNA.

The Protective Layer as an Extension of the Apoplast

IAWA Journal ◽  
1993 ◽  
Vol 14 (2) ◽  
pp. 163-171 ◽  
Author(s):  
J. R. Barnett ◽  
P. Cooper ◽  
Lynda J. Bonner
Keyword(s):  
Cell Wall ◽  
Protective Layer ◽  
Xylem Parenchyma ◽  
Pit Membrane ◽  
Parenchyma Cells ◽  
Deep Supercooling ◽  
Dying Cells ◽  
Tylose Formation ◽  
Universal Application

The protective layer between the cell wall and plasmalemma of xylem parenchyma cells has variously been suggested to be involved in protection of the protoplast from attack by autolytic enzymes from neighbouring, dying cells, tylose formation, deep supercooling of xylem, and strengthening of the pit. None of these ideas has universal application to all species in which parenchyma cells possess a protective layer. It is proposed instead, that the protective layer is primarily laid down in order to preserve apoplastic continuity around the protoplast of a lignified cell, bringing the entire plasmalemma surface, and not just that part of it in contact with the porous pit membrane, into contact with the apoplast. If this is so, then other functions may be coincidental, or have arisen secondarily.

Ultrastructural observations on pit membrane alterations and associated effects in elm xylem tissues infected by Ceratocystis ulmi

1978 ◽  
Vol 56 (20) ◽  
pp. 2567-2588 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Protective Layer ◽  
Cavity Formation ◽  
Bordered Pit ◽  
Fibrillar Material ◽  
Host Cytoplasm ◽  
Pit Membrane ◽  
Bordered Pits ◽  
Parenchyma Cells

Gradations in the degree of pit membrane alteration in tissues infected by Ceratocystis ulmi (Buism.) C. Moreau and collected at various intervals after inoculation are described. Membranes of bordered pit pairs are coated and apparently impregnated with bands or masses of osmiophilic material; this coating may be thick and stratified and the pit cavities completely occluded. Similar osmiophilic material also occurs in decreasing amounts over and within membranes of simple or half-bordered pits and within the adjacent protective layer. Various degrees of distention and cavity formation in these pit membranes are associated with the osmiophilic material. Products released into vessels from disintegrating pit membranes seem to be sparse. Host cytoplasm in contiguous parenchyma cells can have diverse reactions.Examination of specimens at various angles established the interrelationship between osmiophilic material and remnants of pit membranes. Variously oriented lamellar-like structures and a fibrillar material intermixed with a more amorphous one characterize the osmiophilic material. The significance of these observations is discussed.

scholarly journals Immunocytochemical Evidence that Secretion of Pectin Occurs During Gel (Gum) and Tylosis Formation in Trees

1998 ◽  
Vol 88 (6) ◽  
pp. 494-505 ◽  
Author(s):  
D. Rioux ◽  
M. Nicole ◽  
M. Simard ◽  
G. B. Ouellette
Keyword(s):  
Protective Layer ◽  
Xylem Parenchyma ◽  
Pectic Polysaccharides ◽  
Future Studies ◽  
Protective Layers ◽  
Fibrillar Material ◽  
Causative Factors ◽  
Vessel Elements ◽  
Parenchyma Cells ◽  
Other Substances

During gel (gum) formation in angiosperm trees, fibrillar material accumulated in protective layers of xylem parenchyma cells before being secreted across half-bordered pit membranes into vessel elements. Immunogold labeling demonstrated that this fibrillar material was mainly composed of partially esterified pectic polysaccharides. The primary wall of expanding tyloses, an extension of the parenchyma protective layer, secreted similar pectic substances to completely block vessel elements. In most studies, these occluding structures were reported to be formed in response to causative factors such as aging processes, injuries, or infections. Current observations support the view that partial to complete embolism, which almost always accompanies these factors, might be the main cause triggering the formation of vessel occlusions. Whereas pectin seems to be the basic component of gels (gums) and of the external layer of tyloses, other substances, such as phenols, were also detected either as a part of these plugs or as accumulations beside them in vessels. Finally, it is proposed that the term ‘gel’ instead of ‘gum’ be used in future studies to describe the occluding material secreted by ray and paratracheal parenchyma cells.

INTERVASCULAR PITTING ACROSS THE ANNUAL RING BOUNDARY IN BETULA PLATYPHYLLA VAR. JAPONICA AND FRAXINUS MANDSHURICA VAR. JAPONICA

IAWA Journal ◽  
2004 ◽  
Vol 25 (2) ◽  
pp. 129-140 ◽  
Author(s):  
Yuzou Sano
Keyword(s):  
Annual Ring ◽  
Peripheral Region ◽  
Betula Platyphylla ◽  
Annual Rings ◽  
Fraxinus Mandshurica ◽  
Common Wall ◽  
Pit Membrane ◽  
Perforation Plates ◽  
Soluble Material ◽  
Ring Boundary

The structure of intervascular pits, located at the boundary between the outermost and the second youngest annual rings in Betula platyphylla var. japonica and Fraxinus mandshurica var. japonica was examined by field-emission scanning electron microscopy. Unilaterally compound pits were present in the intervascular common wall at the annual ring boundary in both species. On the outer annual ring side of the unilaterally compound pits, outlines of pit membranes were curved or trifoliate, and each pit aperture was often elongated and curved. The porosity of the intervascular pit membranes differed between the two species. In B. platyphylla var. japonica, microfibrils were loosely packed in the peripheral region of each pit membrane, and openings of up to 300 nm in width were observed. By contrast, microfibrils were densely packed throughout the entire pit membranes in F. mandshurica var. japonica, and no openings perforating the pit membranes entirely were found. In addition, each species exhibited some unique features. In B. platyphylla var. japonica, extensive ethanol-soluble material was detected not only in the intervascular pits but also on scalariform perforation plates. In F. mandshurica var. japonica, we observed fine curly fibrils of unkown chemical composition in the intervascular pit membranes.

Cerebral autosomo-dominant arteriopathy with subcortical infarctions and leukoencephalopathy

2021 ◽  
Vol 26 (5) ◽  
pp. 30-38
Author(s):  
E. A. Savchuk ◽  
E. P. Golubinskaya ◽  
T. N. Shcherbinina ◽  
G. Yu. Voronin ◽  
E. O. Savchuk ◽  
...  
Keyword(s):  
Clinical Case ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Joint Work ◽  
Genetic Studies ◽  
Small Vessels ◽  
Clinical Case Study ◽  
The Family ◽  
Probable Diagnosis

The article presents an analysis of the literature and a clinical case of a rare disease from the group of diseases of small vessels — cerebral autosomal dominant arteriopathy with subcortical infarction and leukoencephalopathy (CADASIL).It is based on the deposition of osmiophilic granulation material in vessels of small and medium caliber. A mutation in the NOTCH3 gene on chromosome 19p13 leads to significant structural changes in the walls of small arteries due to impaired differentiation and maturation of smooth muscle cells.CADASIL is characterized by four key symptoms: migraines, recurrent ischemic strokes, mental disorders, and cognitive decline. The clinical case study is presented from the standpoint of a multidisciplinary patient-oriented approach of joint work of neurologists and morphologists. On the basis of clinical and laboratory criteria, a probable diagnosis was made. To confirm it, a muscle biopsy was performed (a musculocutaneous flap from the inner surface of the thighs and forearms), in order to conduct light and electron microscopy. The details of the results of the morphological study, which made it possible to verify the patient’s diagnosis, are presented. Differential diagnostic judgments are presented and recommendations for genetic studies in the family, prognosis and treatment of the patient are given.

Functional medial thickening and folding of the internal elastic lamina in coronary spasm

2011 ◽  
Vol 300 (2) ◽  
pp. H423-H430 ◽  
Author(s):  
Yasumi Uchida ◽  
Yasuto Uchida ◽  
Akimasa Matsuyama ◽  
Atsushi Koga ◽  
Yuko Maezawa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Coronary Spasm ◽  
Cellular Level ◽  
Internal Elastic Lamina ◽  
Circular Smooth Muscle ◽  
The Media ◽  
Medial Thickening ◽  
Elastic Lamina

Although there are a number of studies on vasospastic angina, the structural changes at the cellular level that occur in the coronary arterial wall during spasm are not well known. Coronary spasm was induced by brushing the coronary adventitia in nine anesthetized beagles, and structural changes in the spastic coronary segments were examined by light and electron microscopy, making comparisons with the adjacent nonspastic segments. The % diameter stenosis of the spastic segments as measured angiographically was 79.4 ± 12% (mean ± SD). Light microscopic changes in the spastic and nonspastic segments were as follows: medial thickness 1,512 vs. 392 μm ( P < 0.0001) and % diameter and % area stenoses of spastic segment 81.0% and 96.5%, respectively, indicating that spasm was induced by medial thickening. Circular smooth muscle cells (SMCs) in the media were arranged in parallel with the internal (IEL) and external (EEL) elastic lamina in nonspastic segments but radially rearranged in spastic segments. SMCs were classified by their patterns of connection to IEL into six types by electron microscopy. Of these, three contracted and pulled the IEL toward the EEL, causing folding of the IEL and waving of EEL resulting in thickening of the media and narrowing of the lumen. We conclude that coronary spasm was elicited by radial rearrangement of the medial SMCs due to their own contraction and resultant medial thickening and folding of IEL, creating a piston effect to narrow the lumen, i.e., spasm.

Hydra regeneration from recombined ectodermal and endodermal tissue. II. Differential stability in the ectodermal and endodermal epithelial organization

1997 ◽  
Vol 110 (16) ◽  
pp. 1919-1934
Author(s):  
M. Murate ◽  
Y. Kishimoto ◽  
T. Sugiyama ◽  
T. Fujisawa ◽  
H. Takahashi-Iwanaga ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Single Layer ◽  
Strong Interactions ◽  
High Plasticity ◽  
Spherical Structure ◽  
Epithelial Sheet ◽  
Differential Stability ◽  
Tissue Recombination

Hydra tissue consists of the ectodermal and the endodermal layers. When the two layers were separated by procaine treatment and then recombined, the ectodermal epithelial cells spread as a single cell layer over the endoderm as in epiboly in vertebrate embryogenesis, and the resultant spherical structure subsequently regenerated into a complete hydra. In this study, light and electron microscopy were used to examine the structural changes which took place in the cells and tissue during this epibolic ectodermal spreading process. Within a few hours after tissue recombination, the endoderm underwent dramatic changes; it lost its epithelial sheet organization, and turned into a mass of irregularly shaped cells without the apical-basal cell polarity initially present. In contrast, the ectoderm maintained its basic epithelial sheet organization as it spread over the endoderm. Later, the endodermal epithelial cells reorganized themselves into a single-layered epithelial sheet underneath the spreading ectodermal layer. The resultant spherical structure consisted of a single layer of ectodermal epithelial cells outside, a single layer of endodermal epithelial cells inside, and an empty cavity in the center as in normal hydra tissue. This structure regenerated into hydra in the following days. These and other observations demonstrate that the two-layered epithelial sheet organization is highly dynamic, and that its stability is maintained by strong interactions between the two layers in normal hydra. It is suggested that this dynamic nature of the hydra tissue, particularly the high plasticity of the endodermal epithelial sheet organization, may be an important element for the high regenerative capacity of this organism.

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