Quantitative analyses of neuroepithelial cell shapes during bending of the mouse neural plate

1994 ◽  
Vol 342 (1) ◽  
pp. 144-151 ◽  
Author(s):  
Jodi L. Smith ◽  
Gary C. Schoenwolf ◽  
Jan Quan
Keyword(s):  
Neural Plate ◽  
Neuroepithelial Cell ◽  
Cell Shapes ◽  
Quantitative Analyses

Cell cycle and neuroepithelial cell shape during bending of the chick neural plate

1987 ◽  
Vol 218 (2) ◽  
pp. 196-206 ◽  
Author(s):  
Jodi L. Smith ◽  
Gary C. Schoenwolf
Keyword(s):  
Cell Cycle ◽  
Cell Shape ◽  
Neural Plate ◽  
Neuroepithelial Cell

scholarly journals Redundant type II cadherins define neuroepithelial cell states for cytoarchitectonic robustness

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Kou Hiraga ◽  
Yukiko U. Inoue ◽  
Junko Asami ◽  
Mayuko Hotta ◽  
Yuki Morimoto ◽  
...  
Keyword(s):  
Cell Shape ◽  
Individual Cell ◽  
Neural Plate ◽  
Single Type ◽  
Neuroepithelial Cell ◽  
Type Ii ◽  
Double Knockout ◽  
Determine Function ◽  
Neuroepithelial Cells ◽  
Shared Roles

Abstract Individual cell shape and integrity must precisely be orchestrated during morphogenesis. Here, we determine function of type II cadherins, Cdh6, Cdh8, and Cdh11, whose expression combinatorially demarcates the mouse neural plate/tube. While CRISPR/Cas9-based single type II cadherin mutants show no obvious phenotype, Cdh6/8 double knockout (DKO) mice develop intermingled forebrain/midbrain compartments as these two cadherins’ expression opposes at the nascent boundary. Cdh6/8/11 triple, Cdh6/8 or Cdh8/11 DKO mice further cause exencephaly just within the cranial region where mutated cadherins’ expression merges. In the Cdh8/11 DKO midbrain, we observe less-constricted apical actin meshwork, ventrally-directed spreading, and occasional hyperproliferation among dorsal neuroepithelial cells as origins for exencephaly. These results provide rigid evidence that, by conferring distinct adhesive codes to each cell, redundant type II cadherins serve essential and shared roles in compartmentalization and neurulation, both of which proceed under the robust control of the number, positioning, constriction, and fluidity of neuroepithelial cells.

scholarly journals A mechanism for the proliferative control of tissue mechanics in the absence of growth

2018 ◽  
Author(s):  
Min Wu ◽  
Madhav Mani
Keyword(s):  
Tissue Mechanics ◽  
Mechanical Forces ◽  
Adult Tissue ◽  
Differential Growth ◽  
Model Simulations ◽  
Cell Shapes ◽  
Quantitative Analyses ◽  
Proliferative Control ◽  
Inference Techniques ◽  
Contractile Forces

AbstractDuring the development of a multicellular organism, cells coordinate their activities to generate mechanical forces, which in turn drives tissue deformation and eventually defines the shape of the adult tissue. Broadly speaking, it is recognized that mechanical forces can be generated through differential growth and the activity of the cytoskeleton. Based on quantitative analyses of live imaging of the Drosophila dorsal thorax, we suggest a novel mechanism that can generate contractile forces within the plane of an epithelia - via cell proliferation in the absence of growth. Utilizing force inference techniques, we demonstrate that it is not the gradient of junction tension but the divergence of junction-tension associated stresses that induces the area constriction of the proliferating tissue. Using the vertex model simulations, we show that the local averaged stresses can be roughly elevated by a fold of p 2 per cell division without growth. Moreover, this mechanism is robust to disordered cell shapes and the division anisotropy, but can be dominated by growth. In competition with growth, we identify the parameter regime where this mechanism is effective and suggest experiments to test this new mechanism.

scholarly journals Roles of neuroepithelial cell rearrangement and division in shaping of the avian neural plate

Development ◽  
1989 ◽  
Vol 106 (3) ◽  
pp. 427-439
Author(s):  
G.C. Schoenwolf ◽  
I.S. Alvarez
Keyword(s):  
Cell Division ◽  
Fold Increase ◽  
Cell Number ◽  
Neural Plate ◽  
Neuroepithelial Cell ◽  
Cell Rearrangement ◽  
Constant Size ◽  
Division Cell ◽  
Longitudinal Cell ◽  
Number Of Cells

Shaping of the neural plate, one of the most striking events of neurulation, involves rapid craniocaudal extension. In this study, we evaluated the roles of two processes in neural plate extension: neuroepithelial cell rearrangement and cell division. Quail epiblast plugs of constant size were grafted either just rostral to Hensen's node or paranodally and the resulting chimeras were examined at selected times postgrafting. By comparing the size of the original plug, the number of cells it contained and the distribution of cells within it to those same features of the grafts in chimeras, we were able to ascertain that, during transformation of the flat neural plate into the closed neural tube (a period requiring 24 h), the graft undergoes a maximum of 3 rounds of craniocaudal extension (each round of craniocaudal extension was defined as a doubling of graft length, so 3 rounds equaled an 8-fold increase in length). Such extension is accompanied by 2 rounds of cell rearrangement and 2–3 rounds of cell division (cell rearrangement occurred mediolaterally, so each round was defined as a halving of the number of cells in the width of the graft and a doubling of the number of cells in its length; each round of cell division was defined as a doubling of graft cell number). Modeling studies demonstrate that these amounts of cell rearrangement and division are sufficient to approximate the shaping of the neural plate that normally ensues during neurulation, provided that some of the cell division occurs within the longitudinal plane of the neural plate and some within its transverse plane: longitudinal cell division results in craniocaudal extension of the neural plate, whereas transverse cell division results in lateral expansion of the neural plate such as that occurring at its cranial end; cell rearrangement results in craniocaudal extension of the neural plate as well as in its narrowing. In conclusion, our results provide evidence that shaping of the neural plate involves mediolateral cell rearrangement and cell division, with the latter occurring within both the longitudinal and transverse planes of the neural plate.

Evaluation of the roles of intrinsic and extrinsic factors in occlusion of the spinal neurocoel during rapid brain enlargement in the chick embryo

Development ◽  
1986 ◽  
Vol 97 (1) ◽  
pp. 25-46
Author(s):  
Marye E. Desmond ◽  
Gary C. Schoenwolf
Keyword(s):  
Spinal Cord ◽  
Neuroepithelial Cell ◽  
Extrinsic Factors ◽  
Surface Ectoderm ◽  
Intrinsic Factors ◽  
Chick Embryogenesis ◽  
Posterior Neuropore ◽  
Cell Shapes ◽  
Extracellular Materials ◽  
The Brain

The spinal neurocoel normally occludes during the second day of chick embryogenesis as the lateral walls of the spinal cord become apposed closely in the midline. Concomitantly, the brain initiates its rapid and substantial enlargement. Occlusion, although short-lived, might play a major role in brain enlargement. As a result of occlusion, the brain ventricles are sealed off from the external milieu prior to closure of the posterior neuropore, establishing a closed fluid-filled system. The present study focuses on the mechanisms of occlusion of the spinal neurocoel. We tested two postulated intrinsic factors (microtubule-mediated neuroepithelial cell elongation and microfilament-mediated apical neuroepithelial cell constriction) and five extrinsic factors (three mediad pushing forces generated by the somites, perineural extracellular matrix and expanding surface ectoderm; and two stretching forces generated either vertically by pulling of the elongated notochord or longitudinally by elongation of the embryo) in maintaining occlusion. Our results suggest that occlusion is maintained by other, untested intrinsic factors and/or by forces generated within a perineural collar, composed of cellular and extracellular materials, intimately associated with the basal aspects of the spinal cord. Cytoskeletal-mediated changes in cell shapes, pushing forces and vertical and longitudinal tensions are not involved. Further studies are needed to examine the intrinsic properties of the neuroepithelium and the factors initiating occlusion and reopening.

Mechanisms of neurulation: traditional viewpoint and recent advances

Development ◽  
1990 ◽  
Vol 109 (2) ◽  
pp. 243-270 ◽  
Author(s):  
G.C. Schoenwolf ◽  
J.L. Smith
Keyword(s):  
Cell Shape ◽  
Molecular Mechanisms ◽  
Review Article ◽  
Neural Plate ◽  
Neuroepithelial Cell ◽  
Morphogenetic Movements ◽  
Cell Behaviors ◽  
Recent Advances ◽  
Future Challenges ◽  
Shape Changes

In this review article, the traditional viewpoint of how neurulation occurs is evaluated in light of recent advances. This has led to the formulation of the following fundamentals: (1) neurulation, specifically neural plate shaping and bending, is a multifactorial process resulting from forces both intrinsic and extrinsic to the neural plate; (2) neurulation is driven by both changes in neuroepithelial cell shape and other form-shaping events; and (3) forces for cell shape changes are generated by both the cytoskeleton and other factors. Several cell behaviors within the neural plate have been elucidated. Future challenges include identifying cell behaviors within non-neuroepithelial tissues, determining how intrinsic and extrinsic cell behaviors are orchestrated into coordinated morphogenetic movements and elucidating the molecular mechanisms underlying such behaviors.

Remarks on the application of backscattered electron imaging (BEI) to the scanning electron microscopy (SEM) of biological structures

1983 ◽  
Vol 41 ◽  
pp. 484-487
Author(s):  
Etienne de Harven
Keyword(s):  
High Resolution ◽  
Incident Beam ◽  
Spot Size ◽  
Primary Electron ◽  
Critical Point Drying ◽  
Cell Shapes ◽  
High Resolution Images ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Scanning Electron

Biological ultrastructures have been extensively studied with the scanning electron microscope (SEM) for the past 12 years mainly because this instrument offers accurate and reproducible high resolution images of cell shapes, provided the cells are dried in ways which will spare them the damage which would be caused by air drying. This can be achieved by several techniques among which the critical point drying technique of T. Anderson has been, by far, the most reproducibly successful. Many biologists, however, have been interpreting SEM micrographs in terms of an exclusive secondary electron imaging (SEI) process in which the resolution is primarily limited by the spot size of the primary incident beam. in fact, this is not the case since it appears that high resolution, even on uncoated samples, is probably compromised by the emission of secondary electrons of much more complex origin.When an incident primary electron beam interacts with the surface of most biological samples, a large percentage of the electrons penetrate below the surface of the exposed cells.

In situ microprobe quantitation of inorganic particle burden in paraffin sections of lung tissue

1988 ◽  
Vol 46 ◽  
pp. 990-991
Author(s):  
Jerrold L. Abraham
Keyword(s):  
Lung Tissue ◽  
Quantitative Information ◽  
Particulate Material ◽  
Paraffin Sections ◽  
Tissue Samples ◽  
Qualitative And Quantitative ◽  
The Past ◽  
Quantitative Analyses ◽  
Data Result

Inorganic particulate material of diverse types is present in the ambient and occupational environment, and exposure to such materials is a well recognized cause of some lung disease. To investigate the interaction of inhaled inorganic particulates with the lung it is necessary to obtain quantitative information on the particulate burden of lung tissue in a wide variety of situations. The vast majority of diagnostic and experimental tissue samples (biopsies and autopsies) are fixed with formaldehyde solutions, dehydrated with organic solvents and embedded in paraffin wax. Over the past 16 years, I have attempted to obtain maximal analytical use of such tissue with minimal preparative steps. Unique diagnostic and research data result from both qualitative and quantitative analyses of sections. Most of the data has been related to inhaled inorganic particulates in lungs, but the basic methods are applicable to any tissues. The preparations are primarily designed for SEM use, but they are stable for storage and transport to other laboratories and several other instruments (e.g., for SIMS techniques).

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