Experimental analysis of the extension of the dorsal marginal zone in Pleurodeles waltl gastrulae

The capacity for extension of the dorsal marginal zone (DMZ) in Pleurodeles waltl gastrulae was studied by scanning electron microscopy and grafting experiments. At the onset of gastrulation, the cells of the animal pole (AP) undergo important changes in shape and form a single layer. As gastrulation proceeds, the arrangement of cells also changes in the noninvoluted DMZ: radial intercalation leads to a single layer of cells. Grafting experiments involving either AP or DMZ explants were performed using a cell lineage tracer. When rotated 90 degrees or 180 degrees, grafted DMZ explants were able to involute normally and there was extension according to the animal-vegetal axis of the host. In contrast, neither single nor bilayered explants from AP involutes completely, and neither extends when grafted in place of the DMZ. Furthermore, when inside of the host, these AP grafts curl up and inhibit the closure of the blastopore. Once transplanted to the AP region, the DMZ showed no obvious autonomous extension. DMZs cultured in vitro showed little extension and this only from the late gastrula stage onward. Removal of blastocoel roof blocked involution to a varied extent, depending on the developmental stage of the embryos. From these results, it is argued that differences could well exist in the mechanism of gastrulation between anuran and urodele embryos. That migrating mesodermal cells play a major role in urodele gastrulation is discussed.

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Initiation of mesodermal cell migration and spreading relative to gastrulation in the urodele amphibian Pleurodeles waltl

Development ◽

10.1242/dev.105.2.351 ◽

1989 ◽

Vol 105 (2) ◽

pp. 351-363 ◽

Cited By ~ 3

Author(s):

D.-L. Shi ◽

T. Darribere ◽

K.E. Johnson ◽

J.-C. Boucaut

Keyword(s):

Cell Migration ◽

Marginal Zone ◽

Gastrula Stage ◽

Cell Stage ◽

Animal Pole ◽

Mesodermal Cell ◽

Marginal Cells ◽

Pleurodeles Waltl ◽

Early Gastrula

We have investigated the autonomous migration of marginal cells and their interactions with extracellular matrix (ECM) located on the inner surface of the blastocoel roof in the urodele amphibian, Pleurodeles waltl, using a novel in vitro migration assay. Animal hemispheres containing equatorial cells removed at different cleavage stages and dorsal marginal zone (DMZ) explants of early gastrula stage were cultured either on fibronectin (FN)-coated or ECM-conditioned substrata. In explanted animal hemispheres, dorsal marginal cells showed autonomous migration on FN-coated substratum at the same time as the onset of gastrulation in control embryos. They acquired this capacity at least at the 32-cell stage, whereas lateral and ventral marginal cells acquired it after the 64-cell stage. DMZ outgrowths of early gastrula stage exhibited autonomous spreading on both substrata. In addition, we showed that they spread preferentially toward the animal pole when deposited on substratum conditioned by the dorsal roof of the blastocoel. By culturing dissociated marginal cells on ECM- conditioned substratum, we also found that increased spreading capacity of marginal cells was related to the initiation of their migration. A comparative study of the migration of marginal cells in ultraviolet (u.v.)-irradiated and normal embryos was also made. The results indicate that dorsal marginal cell migration was absent or dramatically reduced by u.v.-irradiation. These results suggest that the differential acquisition in the spreading capacity both in timing and in intensity around the marginal zone was correlated with the sequential involution of mesodermal cells in the course of gastrulation.

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Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055448 ◽

1982 ◽

Vol 40 ◽

pp. 520-521

Author(s):

Ann Chidester Van Orden ◽

John L. Chidester ◽

Anna C. Fraker ◽

Pei Sung

Keyword(s):

Electron Microscopy ◽

Corrosion Behavior ◽

Anodic Polarization ◽

Saline Solution ◽

Saturated Calomel Electrode ◽

Physiological Saline ◽

X Ray ◽

Physiological Saline Solution ◽

Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

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Scanning Electron Microscopy of Staphylococcus Epidermidis Adherence to Continuous Ambulatory Peritoneal Dialysis Catheters

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119429 ◽

1985 ◽

Vol 43 ◽

pp. 520-521

Author(s):

William J. Lamoreaux ◽

David L. Smalley ◽

Larry M. Baddour ◽

Alfred P. Kraus

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Peritoneal Dialysis ◽

Continuous Ambulatory Peritoneal Dialysis ◽

Staphylococcus Epidermidis ◽

Sterile Saline ◽

Intravascular Devices ◽

Capd Patient ◽

Scanning Electron

Infections associated with the use of intravascular devices have been documented and have been reported to be related to duration of catheter usage. Recently, Eaton et al. reported that Staphylococcus epidermidis may attach to silastic catheters used in continuous ambulatory peritoneal dialysis (CAPD) treatment. The following study presents findings using scanning electron microscopy (SEM) of S. epidermidis adherence to silastic catheters in an in vitro model. In addition, sections of polyvinyl chloride (PVC) dialysis bags were also evaluated by SEM.The S. epidermidis strain RP62A which had been obtained in a previous outbreak of coagulase-negative staphylococcal sepsis at local hospitals was used in these experiments. The strain produced surface slime on exposure to glucose, whereas a nonadherent variant RP62A-NA, which was also used in these studies, failed to produce slime. Strains were grown overnight on blood agar plates at 37°C, harvested from the surface and resuspended in sterile saline (0.85%), centrifuged (3,000 rpm for 10 minutes) and then washed twice in 0.1 M phosphate-buffered saline at pH 7.0. Organisms were resuspended at a concentration of ca. 106 CFU/ml in: a) sterile unused dianeal at 4.25% dextrose, b) sterile unused dianeal at 1.5% dextrose, c) sterile used dialysate previously containing 4.25% dextrose taken from a CAPD patient, and d) sterile used dialysate previously containing 1.5% dextrose taken from a CAPD patient.

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The Mesothelial Cell as a Non-Thrombogenic Surface

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661149 ◽

1984 ◽

Vol 52 (02) ◽

pp. 102-104 ◽

Cited By ~ 25

Author(s):

L J Nicholson ◽

J M F Clarke ◽

R M Pittilo ◽

S J Machin ◽

N Woolf

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Blood Flow ◽

Cell Surface ◽

Mesothelial Cell ◽

Mesothelial Cells ◽

Plastic Film ◽

In Vitro System ◽

Scanning Electron

SummaryA technique for harvesting mesothelial cells is described. This entails collagenase digestion of omentum after which the cells can be cultured. The technique has been developed using the rat, but has also been successfully applied to human tissue. Cultured rat mesothelial cells obtained in this way have been examined by scanning electron microscopy. Rat mesothelial cells grown on plastic film have been exposed to blood in an in vitro system using a Baumgartner chamber and have been demonstrated to support blood flow. No adhering platelets were observed on the mesothelial cell surface. Fibroblasts similarily exposed to blood as a control were washed off the plastic.

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Study of Phosphocalcic Glasses from SiO2-CaO-P2O5 System with and Without Silver II. The bioactivity analysis by FTIR, SEM methods and microbiological study of silver-doped glasses

Revista de Chimie ◽

10.37358/rc.17.6.5639 ◽

2017 ◽

Vol 68 (6) ◽

pp. 1188-1192

Author(s):

Daniela Avram ◽

Nicolae Angelescu ◽

Dan Nicolae Ungureanu ◽

Ionica Ionita ◽

Iulian Bancuta ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Body Fluid ◽

Pathogenic Bacteria ◽

De Novo ◽

Microbiological Examination ◽

Doped Glasses ◽

P2o5 System ◽

Scanning Electron

The study in vitro of the glass powders bioactivity was performed by soaking them in simulated body fluid for 3 to 21 days at a temperature of 37�C and pH = 7.20. The synthesis de novo of hydroxyapatite, post soaking was confirmed by Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The study of the antimicrobial activity was performed by microbiological examination on two strains of pathogenic bacteria involved in postoperative nosocomial infections.

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Synthesis and Evaluation of AlgNa-g-poly(QCL-co-HEMA) Hydrogels as Platform for Chondrocyte Proliferation and Controlled Release of Betamethasone

International Journal of Molecular Sciences ◽

10.3390/ijms22115730 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5730

Author(s):

Jomarien García-Couce ◽

Marioly Vernhes ◽

Nancy Bada ◽

Lissette Agüero ◽

Oscar Valdés ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Controlled Release ◽

Biomedical Applications ◽

Release Kinetics ◽

Cell Types ◽

Tissue Engineering Scaffolds ◽

Almost All ◽

Scanning Electron

Hydrogels obtained from combining different polymers are an interesting strategy for developing controlled release system platforms and tissue engineering scaffolds. In this study, the applicability of sodium alginate-g-(QCL-co-HEMA) hydrogels for these biomedical applications was evaluated. Hydrogels were synthesized by free-radical polymerization using a different concentration of the components. The hydrogels were characterized by Fourier transform-infrared spectroscopy, scanning electron microscopy, and a swelling degree. Betamethasone release as well as the in vitro cytocompatibility with chondrocytes and fibroblast cells were also evaluated. Scanning electron microscopy confirmed the porous surface morphology of the hydrogels in all cases. The swelling percent was determined at a different pH and was observed to be pH-sensitive. The controlled release behavior of betamethasone from the matrices was investigated in PBS media (pH = 7.4) and the drug was released in a controlled manner for up to 8 h. Human chondrocytes and fibroblasts were cultured on the hydrogels. The MTS assay showed that almost all hydrogels are cytocompatibles and an increase of proliferation in both cell types after one week of incubation was observed by the Live/Dead® assay. These results demonstrate that these hydrogels are attractive materials for pharmaceutical and biomedical applications due to their characteristics, their release kinetics, and biocompatibility.

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