Ultrastructure of spermatium ontogeny in Puccinia coronata avenae

1978 ◽  
Vol 56 (4) ◽  
pp. 395-403 ◽  
Author(s):  
D. E. Harder ◽  
J. Chong
Keyword(s):  
Outer Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Puccinia Coronata ◽  
Septal Wall ◽  
Periclinal Wall ◽  
Puccinia Coronata Avenae

Spermatium formation in Puccinia coronata avenae was concluded to be annellidic but with some phialidic analogies. The spermatiophore wall consisted of a prominent outer layer and a very thin inner layer. During formation of the first spermatium initial, the apical end of the spermatiophore became somewhat swollen and a septum was then formed centripetally at the base of the swelling to delimit the primary spermatium. The wall layers of the first spermatium were derived from the wall layers of the spermatiophore. The mature septum consisted of two bilayered walls separated by a clear septal lamella. The upper septal wall formed the basal wall portion of the preceding spermatium and the lower septal wall became the distal wall portion of the succeeding spermatium. The layers of each septal wall were confluent with the inner and outer periclinal wall layers of the developing spermatia. After spermatium secession, the broken outer wall layer left remnants as a basal frill on the spermatium and an annular scar on the spermatiophore. Each succeeding spermatium formed at a near-fixed locus on the spermatiophore. Although the formation of succeeding spermatia appeared superficially to be phialidic, examination of wall relationships indicated that the formation of each successive spermatium recapitulated the holoblastic first spermatium.As the spermatia matured, the outer wall layer, including the basal frill, gradually dissipated. The thickness of the spermatium wall was maintained by expansion of the inner layer. In mature spermatia, the inner layer comprised the bulk of the wall, and the outer layer was left as a thin tenuous band surrounding the spermatium.

Cell wall structures of Epicoccum nigrum (Hyphomycetes)

1973 ◽  
Vol 51 (5) ◽  
pp. 1071-1073 ◽  
Author(s):  
J. A. Brushaber ◽  
R. H. Haskins
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Outer Layer ◽  
Secondary Wall ◽  
Outer Wall ◽  
Wall Layer ◽  
Wall Material ◽  
Primary Wall ◽  
Electron Dense Material ◽  
Wall Structures

Two structurally distinct types of secondary wall layers are present in older hyphae in addition to the primary wall. A coarsely fibrous outer wall layer often becomes quite massive and frequently fuses with the outer wall layers of adjacent cells in the formation of hyphal strands. The uneven deposition of this outer layer often produces large verrucosities. The inner secondary wall layer is relatively electron transparent and contains a reticulum of electron-dense lines. The interface of the inner secondary wall with the cytoplasm is often very irregular, and sections of the plasma membrane are frequently overlain by wall material. The outer secondary wall of conidia is composed of an electron-dense material different from that of the outer wall of hyphae. Cells in the multicellular conidia tend to be polyhedral in shape with either very thick primary walls or thin primary walls having a thick inner wall deposit.

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.

Direct measurement of transverse residual strains in aorta

1996 ◽  
Vol 270 (2) ◽  
pp. H750-H759 ◽  
Author(s):  
H. C. Han ◽  
Y. C. Fung
Keyword(s):  
Stress State ◽  
Outer Layer ◽  
Residual Strain ◽  
Longitudinal Axis ◽  
Outer Wall ◽  
Residual Strains ◽  
Stress States ◽  
Sectional Surface ◽  
Thoracic And Abdominal ◽  
Load State

Residual strains were measured in the porcine aorta. Segments were cut from the aorta perpendicular to its longitudinal axis. Microdots of water-insoluble black ink were sprinkled onto the transverse sectional surface of the segments in the no-load state. The segments were then cut radially, and sectional zero-stress states were approached. The coordinates of selected microdots (2-20 microns) were digitized from photographs taken in the no-load state and the zero-stress state. Residual strains in the transverse section were calculated from the displacement of the microdots. The circumferential residual strains on the inner wall and outer wall were calculated from the circumferential lengths in the no-load state and the zero-stress state. Results show that the circumferential residual strain is negative (compressive) in the inner layer of the aortic wall and positive (tensile) in the outer layer, whereas the radial residual strain is tensile in the inner layer and compressive in the outer layer. This residual strain distribution reduces the stress concentration in the aorta under physiological load. The experimental results compared well with theoretical estimations of a cylindrical model. Regional difference of the residual strain exists and is significant (P < 0.01), e.g., the circumferential residual strains on the inner wall of the ascending, descending thoracic, and abdominal regions of the aorta are -0.133 +/- 0.019, -0.074 +/- 0.020, and -0.046 +/- 0.017 (mean +/- SD), respectively. More radial cuts of a segment produced no significant additional strains. This means that an aortic segment after one radial cut can be considered as the zero-stress state.

Spore wall development in Sphagnum lescurii

1982 ◽  
Vol 60 (11) ◽  
pp. 2394-2409 ◽  
Author(s):  
Roy Curtiss Brown ◽  
Betty E. Lemmon ◽  
Zane B. Carothers
Keyword(s):  
Plasma Membrane ◽  
Outer Layer ◽  
Mature Spore ◽  
Outer Wall ◽  
Spore Wall ◽  
Spore Surface ◽  
Proximal Surface ◽  
Complex Development ◽  
Surface Ornamentation ◽  
Cortical System

The spore wall of Sphagnum is unique in the Bryophyta. The Sphagnum spore exine consists of two layers: an inner, lamellate layer (A layer) and a thick, homogenous, outer layer (B layer). The exine of other mosses consists of only the outermost homogenous layer and, at most, a thin ill-defined opaque layer. During development of the A-layer exine and the intine, a cortical system of evenly spaced microtubules underlies the plasma membrane. The ontogeny of the wall layers is not strictly centripetal. The A-layer exine develops evenly around the young spore immediately after cytokinesis. As the intine is deposited centripetally inside it, the homogenous B-layer exine is deposited outside the first-formed A layer. The B layer is responsible for the primary sculpturing of the spore surface. The mature spore is covered by an outermost perine, which is responsible for secondary surface ornamentation. A trilaesurate aperture develops on the proximal surface of each spore after deposition of the A layer. Ridges of the laesurae develop as a result of deposition of thick areas of intine. The ridges are eventually covered by the outer wall layers, whereas the fissure is covered only by the A layer and a very thin B-layer exine. The complex development of the trilaesurate aperture is evidence that the structure is not merely a mechanically induced "trilete mark" or "scar" resulting from compression of tetrahedrally arranged spores within a sporocyte wall.

Influence of Heat Insulation Material on Thermal Stress of Long Nozzle

2012 ◽  
Vol 535-537 ◽  
pp. 1609-1614 ◽  
Author(s):  
Hui Min Liu
Keyword(s):  
Thermal Stress ◽  
Layer Thickness ◽  
Outer Layer ◽  
Heat Insulation ◽  
Outer Wall ◽  
Symmetric Model ◽  
Insulation Material ◽  
Axially Symmetric ◽  
Coefficient Of Thermal Conductivity ◽  
Heat Insulation Material

To prevent a long nozzle (LN) of non-preheating from rupture caused by thermal shock, heat insulation material (HIM) with a lower coefficient of thermal conductivity (CTC) was compounded in the inner hole (inner layer) or around the outer wall (outer layer), and the thermal stress was investigated. The two-dimension axially symmetric model of LN was proposed by simplifying the structure and boundary conditions. The influences of the HIM to the thermal stress of LN were analyzed by finite element method. The results show that the thermal stress suffered by LN can be drastically reduced by the inner layer, making the slow variation, but when its thickness increases from 2 mm to 3 mm, it almost has no influence on the thermal stress. The maximum thermal stress at the neck of LN reduces with the depression of the CTC at the inner layer thickness of 2 mm. The maximum thermal stress of LN can’t be reduced by outer layer, but the lasting time of higher stress can be shortened, and the thermal stress at the later period of steel-irrigating can be lowed. When the outer layer thickness is more than 2 mm, the increase of it has little influence on the thermal stress of LN, and the change of its CTC has little influence on the thermal stress either. The LN with tri-layer has lower thermal stress during all the period of steel-irrigating.

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