Pit-field distribution, plasmodesmatal frequency, and assimilate flux in the mestome sheath cells of wheat leaves

Planta ◽  
1974 ◽  
Vol 121 (2) ◽  
pp. 97-118 ◽  
Author(s):  
J. Kuo ◽  
T. P. O'Brien ◽  
M. J. Canny
Keyword(s):  
Field Distribution ◽  
Mestome Sheath ◽  
Pit Field ◽  
Plasmodesmatal Frequency ◽  
Wheat Leaves ◽  
Sheath Cells

Development of the Suberized Lamella in the Mestome Sheath of Wheat Leaves

1975 ◽  
Vol 23 (5) ◽  
pp. 783 ◽  
Author(s):  
TP O'Brien ◽  
J Kuo
Keyword(s):  
Cell Walls ◽  
Tracheary Element ◽  
Tracheary Elements ◽  
Mestome Sheath ◽  
Suberized Lamella ◽  
Tangential Wall ◽  
Sieve Tubes ◽  
Wheat Leaves ◽  
Cytoplasmic Structures ◽  
Sheath Cells

The suberized lamella in the cell walls of the mestome sheath of wheat leaves developed asynchronously. The lamella formed first in the cells which were adjacent to the protophloem sieve tubes and formed last in the cells that abutted on the tracheary elements. In the latter case, the suberized lamella formed first in the outer tangential and radial walls and last in the inner tangential wall adjacent to the tracheary element. Eventually, the suberization was completed opposite the tracheary elements and the cell walls developed tertiary thickenings in all mestome sheath cells. Cytoplasmic structures that were clearly involved in suberin synthesis and the development of tertiary thickenings could not be identified.

Water Pathways in Wheat Leaves. IV. The Interpretation of Images of a Fluorescent Apoplastic Tracer

1988 ◽  
Vol 15 (4) ◽  
pp. 541 ◽  
Author(s):  
MJ Canny
Keyword(s):  
Cell Walls ◽  
Water Movement ◽  
Freeze Substitution ◽  
Sheath Cell ◽  
High Concentration ◽  
Mestome Sheath ◽  
Wheat Leaves ◽  
Apoplastic Tracer ◽  
Very High ◽  
Wall Components

Sections of wheat leaves fed with the fluorescent apoplastic tracer sulforhodamine G (SR) through the xylem were prepared by freeze-substitution and resin embedding. The distribution of fluorescence intensity (FI) of the tracer was measured by microspectrofluorometry at a resolution of 0.4 �m. SR was found to move within cell walls in restricted paths less than 200 nm wide. The name 'nanopaths' is suggested for these. The highest FI was found around the mestome-sheath / parenchyma-sheath border on the xylem side, and was shown to be due, not to binding of the tracer to wall components, but to the generation of a very high concentration of SR there by the separation of water from the solute. This separation cannot be evaporative but must be osmotic, and is presented as evidence of a major symplastic water movement starting at the parenchyma sheath cell membrane. The main resistance to water loss from the veins is at the mestome sheath and appears to be controlled by the suberised lamellae.

Development of mestome sheath cells in leaves ofAegilops comosa var.thessalica

PROTOPLASMA ◽  
1979 ◽  
Vol 100 (2) ◽  
pp. 139-153 ◽  
Author(s):  
E. P. Eleftheriou ◽  
I. Tsekos
Keyword(s):  
Mestome Sheath ◽  
Sheath Cells

scholarly journals Leaf blade and midrib anatomy of two sugarcane cultivars of Bangladesh

1970 ◽  
Vol 18 ◽  
pp. 66-73 ◽  
Author(s):  
N Joarder ◽  
AK Roy ◽  
SN Sima ◽  
K Parvin
Keyword(s):  
Leaf Blade ◽  
Bundle Sheath ◽  
Vascular Bundles ◽  
Abaxial Epidermis ◽  
Sugarcane Cultivar ◽  
Mestome Sheath ◽  
Bulliform Cells ◽  
Kranz Anatomy ◽  
Bundle Sheath Cells ◽  
Sheath Cells

Context: Kranz anatomy of locally developed sugarcane cultivars were studied in relation to C4 vascular arrangement.   Objective: The objective of this study was to make gross cross-sectional anatomy and quantitative assessment of the anatomic traits of the leaf-blade and midrib of the sugarcane cultivars.   Materials and Methods: Leaf blade and leaf sheath of two sugarcane cultivars Ishurdi 20 and Ishurdi 32 were used as the materials. Free hand section with appropriate stain were used. Sections were studied using an advanced biological system microscope fitted with motic camera. Anatomic traits were studied through motic image plus J 1.0 software using Macintosh computer.   Results: Three sized vascular bundles and significant differences in distance between those vascular bundles were noted. Ishurdi 32 possessed two sized vascular bundles. Large vascular bundles characters by two large metaxylem vessels on either side of protoxylem. Phloem well developed. Intermediate and small bundles lack metaxylem vessels and protoxylem, but have metaphloem with thick and thin walled sieve tubes. Bundle sheaths have extended to upper and lower epidermis but for small bundle it is extended to abaxial epidermis. Vascular bundles are almost completely surrounded by chlorenchymatous bundle sheath and associated with hypodermal sclerenchyma on both abaxially and adaxially except small blade bundles which associated with the abaxial sclerenchyma. Bundle sheath cells were smaller in large and larger in other two types of vascular bundle. An inner mestome sheath with thickened walls is always present round the phloem and metaxylem around all or part of the xylem in large and intermediate bundles. In small bundles mestome sheath is altogether absent. Bulliform cells with varied area were present on the adaxial epidermis opposite to small vascular bundles. Midrib anatomy consists of central large vascular bundles lacking bundle sheath cells pushed deep inside parenchymatous hypodermis from abaxial hypodermal sclerenchyma girders. Lack of Kranz traits, and bundle sheath cells have transformed into sclerenchymatous bundle cover. Central mid-rib large bundle flanked by 3-10 small bundles on either side of midrib which have Kranz system of anatomy. Midrib region have continuous hypodermis consists of sclerenchyma cells and it is few layer (Ishurdi 32) to multilayer (Ishurdi 20).   Conclusion: Kranz system with well developed bundle sheath associated with Kranz mesophil in the leaf blade were observed but Kranz tissue absent in midrib region. Large and small vascular bundles alternate all alone the leaf blade. Bulliform cell well develop indicates zeric adaptation. Two cultivars differ in respect of quantitative expression of Kranz tissue.   Keywords: Sugarcane cultivar; Kranz tissue; bulliform cells; mestome sheath. DOI: http://dx.doi.org/10.3329/jbs.v18i0.8778 JBS 2010; 18(0): 66-73

Kranz distinctive cells in the culm of ArundineUa (Arundinelleae; Panicoideae; Poaceae)

Bothalia ◽  
1990 ◽  
Vol 20 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Evangelina Sanchez ◽  
Mirta O. Arriaga ◽  
Roger P. Ellis
Keyword(s):  
South America ◽  
Small Groups ◽  
Peripheral Zone ◽  
Bundle Sheath ◽  
Vascular Bundles ◽  
Photosynthetic Pathway ◽  
Mestome Sheath ◽  
Bundle Sheath Cells ◽  
Chlorenchyma Cell ◽  
Sheath Cells

The transectional anatomy of photosynthetic flowering culms of Arundinella berteroniana (Schult.) Hitchc. Chase and A. hispida (Willd.) Kuntze from South America and A.  nepalensis Trin. from Africa is described and illustrated. The vascular bundles are arranged in three distinct rings, the outermost being external to a continuous sclerenchymatous band. Each of these peripheral bundles is surrounded by two bundle sheaths, a complete mestome sheath and an incomplete, outer, parenchymatous Kranz sheath, the cells of which contain large, specialized chloroplasts. Kranz bundle sheath extensions are also present. The chlorenchyma tissue is also located in this narrow peripheral zone and is interrupted by the vascular bundles and their associated sclerenchyma. Dispersed throughout the chlorenchyma are small groups of Kranz distinctive cells, identical in structure to the outer bundle sheath cells. No chlorenchyma cell is. therefore, more than two cells distant from a Kranz cell. The structure of the chlorenchyma and bundle sheaths indicates that the C4 photosynthetic pathway is operative in these culms. This study clearly demonstrates the presence of the peculiar distinctive cells in the culms as well as in the leaves of Arundinella. Also of interest is the presence of an inner bundle sheath in the vascular bundles of the culm whereas the bundles of the leaves possess only a single sheath. It has already been shown that Arundinella is a NADP-me C4 type and the anatomical predictor of a single Kranz sheath for NADP-me species, therefore, either does not hold in the culms of this genus or the culms are not NADP-me. This is only the second reported breakdown of this association between MS anatomy and the NADP-me biochemical C4 type.

High Resolution Specimen Area Imaged Under Negligible Field Aberrations

1970 ◽  
Vol 28 ◽  
pp. 540-541 ◽  
Author(s):  
T. Yanaka ◽  
K. Shirota
Keyword(s):  
High Resolution ◽  
Field Distribution ◽  
Image Space ◽  
Beam Deflection ◽  
Objective Lens ◽  
Resolution Limit ◽  
Leakage Flux ◽  
Specimen Area ◽  
Points Of View ◽  
Aberration Theory

It is significant to note field aberrations (chromatic field aberration, coma, astigmatism and blurring due to curvature of field, defined by Glaser's aberration theory relative to the Blenden Freien System) of the objective lens in connection with the following three points of view; field aberrations increase as the resolution of the axial point improves by increasing the lens excitation (k2) and decreasing the half width value (d) of the axial lens field distribution; when one or all of the imaging lenses have axial imperfections such as beam deflection in image space by the asymmetrical magnetic leakage flux, the apparent axial point has field aberrations which prevent the theoretical resolution limit from being obtained.

Field Distribution of Strongly Excited Magnetic Lenses

1975 ◽  
Vol 33 ◽  
pp. 140-141
Author(s):  
M. Strojnik
Keyword(s):  
Flux Density ◽  
Field Distribution ◽  
Optical Axis ◽  
Operating Point ◽  
Pole Piece ◽  
Partial Saturation ◽  
Axial Flux ◽  
The Stability

Magnetic lenses operating in partial saturation offer two advantages in HVEM: they exhibit small cs and cc and their power depends little on the excitation IN. Curve H, Fig. 1, shows that the maximal axial flux density Bz max of one of the lenses investigated changes between points (3) and (4) by 5% as the excitation varies by 40%. Consequently, the designer can relax the requirements concerning the stability of the lens current supplies. Saturated lenses, however, can only be used if (i) unwanted fields along the optical axis can be controlled, (ii) 'wobbling' of the optical axis due to inhomogeneous saturation around the pole piece faces is prevented, (iii) ample ampere-turns can be squeezed into the space available, and (iv) the lens operating point covers a sufficient range of accelerating voltages.

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