Proembryo Development and Suspensor Elongation in Araucaria Juss

1980 ◽  
Vol 28 (6) ◽  
pp. 511 ◽  
Author(s):  
RJ Haines ◽  
N Prakash
Keyword(s):  
Central Region ◽  
Early Stage ◽  
Evolutionary Trends ◽  
Wall Formation ◽  
Cleavage Polyembryony ◽  
Internal Division

Development of the proembryo and suspensor was studied in three species of Araucaria– A cunninghamii, A. bidwillii and A. heterophylla. In all species there are six synchronous free nuclear mitoses followed by wall formation. The subsequent internal division gives rise to a typical U.S.E. conifer proembryo. although the E group includes the conspicuous symmetrical cap, and the U cells are very ephemeral. During all divisions the proembryo is situated in the central region of the archegonium. The cells of the S group subsequently elongate to form the functional suspensor. Cleavage polyembryony does not occur although simple polyembryony is common. The proembryo of Araucaria is considered to have diverged at an early stage of evolution of the conifer proembryo, but to have subsequently undergone considerable specialization in a direction unrelated to evolutionary trends recognizable among other conifers.

scholarly journals Asymmetric Patterns of Visual Field Loss in Primary Angle Closure Glaucoma, High Tension Glaucoma, and Normal Tension Glaucoma

2021 ◽  
Author(s):  
Junhong Jiang ◽  
Cong Ye ◽  
Cong Zhang ◽  
Wenqing Ye ◽  
Xiaoyan Wang ◽  
...  
Keyword(s):  
Central Region ◽  
Early Stage ◽  
Normal Tension Glaucoma ◽  
Angle Closure Glaucoma ◽  
Angle Closure ◽  
Mean Deviation ◽  
Automated Perimetry ◽  
Primary Angle Closure ◽  
Primary Angle Closure Glaucoma ◽  
High Tension

Abstract The data directly comparing the spatial pattern of VF defects between primary angle-closure glaucoma (PACG), high-tension glaucoma (HTG) and normal-tension glaucoma (NTG) is not available. We aim to compare the asymmetric patterns of VF defects in patients with PACG, NTG and HTG across different severity levels. A total of 162 eyes of 114 patients with PACG, 111 eyes of 74 patients with HTG and 148 eyes of 102 patients with NTG were included. VF examinations were performed with standard automated perimetry (HFA, SITA-standard strategy, 24-2), and defects were categorized into 3 stages (early, moderate, and advanced) and each hemifield was divided into 5 regions according to Glaucoma Hemifield Test (GHT). The mean total deviation (TD) of each GHT region was calculated. The relationship between the values of pattern standard deviation (PSD) and mean TD was assessed. In the early stage, nasal region of PACG, central region of HTG and all five regions of NTG in the superior hemifield had significantly worse mean TD than their counterparts in the inferior hemifield. In the moderate stage, three regions of NTG in the superior hemifield had significantly worse mean TD than their inferior counterparts. In the advanced stage, central region of PACG, and central and paracentral regions of HTG in the superior hemifield had significantly worse mean TD than their inferior counterparts. When participants were matched by age, sex and mean deviation, in PACG and HTG eyes, all 5 GHT regions in the superior hemifield had worse mean TD than that that of their inferior-hemifield counterparts; however, the differences were not statistically significant. In NTG eyes, the paracentral, nasal, arcuate 1 and arcuate 2 regions in the superior hemifield had significantly worse mean TDs than their inferior counterparts. The superior hemifield is affected more severely than the inferior hemifield in all 3 subtypes of primary glaucoma. This asymmetric tendency was more pronounced in NTG compared to PACG and HTG.

Determination of patterning in the pollen wall of Lilium henryi

1983 ◽  
Vol 63 (1) ◽  
pp. 191-208
Author(s):  
J.M. Sheldon ◽  
H.G. Dickinson
Keyword(s):  
Plasma Membrane ◽  
Early Stage ◽  
Critical Role ◽  
Late Prophase ◽  
Wall Formation ◽  
Pattern Determination ◽  
Mother Cells ◽  
Cell Fragments ◽  
Insight Into

Centrifugation of living pollen mother cells of Lilium henryi has permitted the modifications of complex walls developed on the four daughter microspores. This experimental approach has not only provided an insight into the mechanism by which patterning is established, but has also identified the stages in cell development when wall determinants are present. These determinants can be first detected late in the meiotic prophase, but are not necessarily active at the cell surface at this early stage. The fact that treatment during cytokinesis may affect subsequent wall formation, combined with the obvious interference of the colpus with the spore patterning, indicates pattern determination to be a lengthy process, commencing during late prophase and reaching completion in the young tetrad. The study of walls formed on enucleate cell fragments suggests that neither the spindle nor the cytoskeleton is intimately involved in formation of the basic reticulate patterning. It is proposed that material is inserted into the mosaic of the plasma membrane and is reorganized biophysically to form contiguous ‘plates’, which then modify the properties of the membrane in such a way that the cytoplasmic protrusions that constitute the first stages of wall formation only develop in the interstices between them. Changes in the plasma membrane have been detected over this period and it seems that a population of coated vesicles is closely involved in these events. Examination of the cytoskeleton of the young spore suggests that microtubules play a critical role in the positioning of the colpus, and reveals ways by which only small changes in this skeleton could give rise to multicolporate grains.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

Alterations in the number of motoneurons containing immunoreactive calcitonin gene-related peptide(CGRP)& choline acetyltransferase(ChAT) in the cervical spinal cord of the wobbler mouse during the development of the motoneuron disease

1995 ◽  
Vol 53 ◽  
pp. 970-971
Author(s):  
L. Vacca-Galloway ◽  
Y.Q. Zhang ◽  
P. Bose ◽  
S.H. Zhang
Keyword(s):  
Spinal Cord ◽  
Early Stage ◽  
Cervical Spinal Cord ◽  
Wild Type Mouse ◽  
Reflex Response ◽  
Mouse Strains ◽  
Behavioral Tests ◽  
Wobbler Mouse ◽  
Stage 4 ◽  
Stage 1

The Wobbler mouse (wr) has been studied as a model for inherited human motoneuron diseases (MNDs). Using behavioral tests for forelimb power, walking, climbing, and the “clasp-like reflex” response, the progress of the MND can be categorized into early (Stage 1, age 21 days) and late (Stage 4, age 3 months) stages. Age-and sex-matched normal phenotype littermates (NFR/wr) were used as controls (Stage 0), as well as mice from two related wild-type mouse strains: NFR/N and a C57BI/6N. Using behavioral tests, we also detected pre-symptomatic Wobblers at postnatal ages 7 and 14 days. The mice were anesthetized and perfusion-fixed for immunocytochemical (ICC) of CGRP and ChAT in the spinal cord (C3 to C5).Using computerized morphomety (Vidas, Zeiss), the numbers of IR-CGRP labelled motoneurons were significantly lower in 14 day old Wobbler specimens compared with the controls (Fig. 1). The same trend was observed at 21 days (Stage 1) and 3 months (Stage 4). The IR-CGRP-containing motoneurons in the Wobbler specimens declined progressively with age.

Automated high-resolution microscopy: the approaches so far

1987 ◽  
Vol 45 ◽  
pp. 58-61
Author(s):  
W. O. Saxton
Keyword(s):  
High Resolution ◽  
Early Stage ◽  
Automatic Recording ◽  
Microprocessor Control ◽  
Alternative Systems ◽  
Electron Image ◽  
Complete Automation ◽  
Analysis System ◽  
High Resolution Microscopy

Recent commercial microscopes with internal microprocessor control of all major functions have already demonstrated some of the benefits anticipated from such systems, such as continuous magnification, rotation-free diffraction and magnification, automatic recording of mutually registered focal series, and fewer control knobs. Complete automation of the focusing, stigmating and alignment of a high resolution microscope, allowing focal series to be recorded at preselected focus values as well, is still imminent rather than accomplished, however; some kind of image pick-up and analysis system, fed with the electron image via a TV camera, is clearly essential for this, but several alternative systems and algorithms are still being explored. This paper reviews the options critically in turn, and stresses the need to consider alignment and focusing at an early stage, and not merely as an optional extension to a basic proposal.

Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing

1993 ◽  
Vol 51 ◽  
pp. 1116-1117
Author(s):  
C. S. Lin ◽  
W. A. Chiou ◽  
M. Meshii
Keyword(s):  
Intermetallic Compound ◽  
Reaction Rate ◽  
Diffusion Rate ◽  
Early Stage ◽  
Zinc Bath ◽  
Steel Sheets ◽  
Direct Observations ◽  
Solid Iron ◽  
Iron And Zinc ◽  
Ternary Intermetallic Compound

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

1596: Choices for Definitive Treatment of Early-Stage Prostate Cancer: Results from the Compare Registry

2006 ◽  
Vol 175 (4S) ◽  
pp. 514-514
Author(s):  
David G. McLeod ◽  
Oliver Sartor ◽  
Paul F. Schellhammer ◽  
Anthony V. D'Amico ◽  
Susan Halabi ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Early Stage ◽  
Definitive Treatment

644: Cathepsin D is a Marker for Early Stage Renal Cell Cancer and Predicts the Presence of Distant Metastases

2005 ◽  
Vol 173 (4S) ◽  
pp. 175-175
Author(s):  
Axel S. Merseburger ◽  
Joerg Hennenlotter ◽  
Perikles Simon ◽  
Marcus Horstmann ◽  
Arnulf Stenzl ◽  
...  
Keyword(s):  
Renal Cell Cancer ◽  
Renal Cell ◽  
Cathepsin D ◽  
Early Stage ◽  
Cell Cancer ◽  
Distant Metastases

1068: TP53 Gene Mutations as a Prognostic Marker for PSA Progression in Early Stage Prostate Cancer

2004 ◽  
Vol 171 (4S) ◽  
pp. 282-282
Author(s):  
Markus D. Sachs ◽  
Horst Schlechte ◽  
Katrin Schiemenz ◽  
Severin V. Lenk ◽  
Dietmar Schnorr ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Prognostic Marker ◽  
Early Stage ◽  
Gene Mutations ◽  
Tp53 Gene ◽  
Psa Progression ◽  
Tp53 Gene Mutations
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