Extracellular matrix modifications in the interdigital spaces of the chick embryo leg bud during the formation of ectopic digits

1996 ◽  
Vol 193 (4) ◽  
Author(s):  
JuanM. Hurle ◽  
Alfonso Colombatti
1992 ◽  
Vol 102 (2) ◽  
pp. 373-385 ◽  
Author(s):  
M.T. Armstrong ◽  
P.B. Armstrong

The processes responsible for epithelial spreading during wound healing and embryonic morphogenesis were investigated in an organ culture model in which an epithelial tissue (chick embryo pigmented retinal epithelium) spread over the surface of an aggregate of mesenchyme cells (chick embryo cardiac mesenchyme). The heart mesenchyme aggregate is differentiated into a core of stellate cells associated with a fibronectin-poor matrix surrounded by a cortical zone, 2–5 cells in thickness, of flattened cells embedded in a fibronectin-rich extracellular matrix. Envelopment of the mesenchyme aggregate is accompanied by a movement of the cells and the fibronectin-rich extracellular matrix of the cortex over the core tissue in advance of the spreading pigmented retina tissue. Three distinct processes were identified as contributing to epithelial spreading in this system: (1) active migration of the pigmented retinal epithelium; (2) active contraction of the cortical cells of the mesenchyme aggregate to tow the attached epithelial tissue over the mesenchyme aggregate; and (3) ingression of surface-located cells of the mesenchyme aggregate to decrease the exposed surface area by decreasing the number of cells at the surface.


1993 ◽  
Vol 121 (1) ◽  
pp. 201-212 ◽  
Author(s):  
G M Bressan ◽  
D Daga-Gordini ◽  
A Colombatti ◽  
I Castellani ◽  
V Marigo ◽  
...  

The fine distribution of the extracellular matrix glycoprotein emilin (previously known as glycoprotein gp115) (Bressan, G. M., I. Castellani, A. Colombatti, and D. Volpin. 1983. J. Biol. Chem. 258: 13262-13267) has been studied at the ultrastructural level with specific antibodies. In newborn chick aorta the protein was exclusively found within elastic fibers. In both post- and pre-embedding immunolabeling emilin was mainly associated with regions where elastin and microfibrils are in close contact, such as the periphery of the fibers. This localization of emilin in aorta has been confirmed by quantitative evaluation of the distribution of gold particles within elastic fibers. In other tissues, besides being associated with typical elastic fibers, staining for emilin was found in structures lacking amorphous elastin, but where the presence of tropoelastin has been demonstrated by immunoelectron microscopy. This was particularly evident in the oxitalan fibers of the corneal stroma, in the Descemet's membrane, and in the ciliary zonule. Analysis of embryonic aorta revealed the presence of emilin at early stages of elastogenesis, before the appearance of amorphous elastin. Immunofluorescence studies have shown that emilin produced by chick embryo aorta cells in culture is strictly associated with elastin and that the process of elastin deposition is severely altered by the presence of antiemilin antibodies in the culture medium. The name of the protein was derived from its localization at sites where elastin and microfibrils are in proximity (emilin, elastin microfibril interface located protein).


Development ◽  
1983 ◽  
Vol 78 (1) ◽  
pp. 195-209
Author(s):  
J. M. Hurle ◽  
M. A. Fernandez-Teran

There is recent evidence showing that in addition to the well-known mesenchymal necrotic mechanism involved in the disappearance of the interdigital membranes, the ectodermal tissue may also play an active role in the formation of the free digits of most vertebrates. Ultrastructural study of the regressing interdigital membrane of the chick leg revealed significant changes at the epitheliomesenchymal interface. Disruptions of the ectodermal basal lamina and an intense deposition of collagenous material were the most conspicuous changes observed in the extracellular matrix. In addition the basal ectodermal cells showed prominent cell processes projected into the mesenchymal core of the membrane, and mesenchymal macrophages appeared to migrate through the epithelial tissue to be detached into the amniotic sac. It is concluded from our results that the elimination of the interdigital membranes is a complex process requiring the interaction of all the tissue components of the membrane.


Development ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 71-87
Author(s):  
Trent D. Stephens ◽  
N. S. Vasan ◽  
James W. Lash

Little is known at the present time about the molecular basis and mechanisms of morphogenesis. The present study is an attempt to determine what influence the extracellular matrix has on the initial outgrowth of the limb bud. Stage -12 to -18 chick embryo lateral plates were examined in relation to proline and sulfate incorporation into collagen and proteoglycan. The flank and limbs incorporated the same amount of labeled proline and sulfate before stage 16. At stage 16 the flank began to incorporate more of both isotopes until at stage 18 there was twice as much incorporation into the flank as into the limbs. The flank and limbs contained the same type of collagen during the period examined. The limbs contained both large and small proteoglycans but the flank contained only small proteoglycans. These data suggest that the extracellular matrix in the flank and limb regions may play a role in limb outgrowth and that the limb buds at these stages may be more inclined toward cartilage development.


1991 ◽  
Vol 99 (2) ◽  
pp. 431-441
Author(s):  
A.J. Brown ◽  
E.J. Sanders

In the gastrulating chick embryo, the mesoderm cells arise from the epiblast layer by ingression through the linear accumulation of cells called the primitive streak. The mesoderm cells emerge from the streak with a fibroblastic morphology and proceed to move away from the mid-line of the embryo using, as a substratum, the basement membrane of the overlying epiblast and the extracellular matrix. We have investigated the roles of fibronectin and laminin as putative substrata for mesoderm cells using complementary in vivo and in vitro methods. We have microinjected agents into the tissue space adjacent to the primitive streak of living embryos and, after further incubation, we have examined the embryos for perturbation of the mesoderm tissue. These agents were: cell-binding regions from fibronectin (RGDS) and laminin (YIGSR), antibodies to these glycoproteins, and a Fab' fragment of the antibody to fibronectin. We find that RGDS, antibody to fibronectin, and the Fab' fragment cause a decrease in the number of mesoderm cells spread on the basement membrane, and a perturbation of cell shape suggesting locomotory impairment. No such influence was seen with YIGSR or antibodies to laminin. These results were extended using in vitro methods in which mesoderm cells were cultured in fibronectin-free medium on fibronectin or laminin in the presence of various agents. These agents were: RGDS; YIGSR; antibodies to fibronectin, fibronectin receptor, laminin and vitronectin; and a Fab' fragment of the fibronectin antiserum. We find that cell attachment and spreading on fibronectin is impaired by RGDS, antiserum to fibronectin, the Fab' fragment of fibronectin antiserum, and antiserum to fibronectin receptor. The results suggest that although the RGDS site in fibronectin is important, it is probably not the only fibronectin cell-binding site involved in mediating the behaviour of the mesoderm cells. Cells growing on laminin were perturbed by YIGSR, RGDS and antibodies to laminin, suggesting that mesoderm cells are able to recognise at least two sites in the laminin molecule. We conclude that the in vivo dependence of mesoderm cells on fibronectin is confirmed, but that although these cells have the ability to recognise sites in laminin as mediators of attachment and spreading, the in vivo role of this molecule in mesoderm morphogenesis is not yet certain.


1980 ◽  
Vol 87 (1) ◽  
pp. 14-22 ◽  
Author(s):  
P Hsieh ◽  
R Segal ◽  
L B Chen

We have used fluorescein isosthiocyanate-conjugated gelatin (FITC-gelatin) (1 mg/ml) to localize cell surface fibronectin in unfixed live cells in cultures. FITC-gelatin stains the fibronectin matrix on primary cultures of rat and chick embryo fibroblasts as well as untransformed, established cell lines. In live cultured cells, fibronectin in many areas of the extracellular matrix is inaccessible to antibody and cannot be visualized by immunofluorescence staining. In contrast, fibronectin in these areas is fully stainable by FITC-gelatin. At a low concentration (20 micrograms/ml), FITC-gelatin stains the fibronectin matrix of primary cultured cells but not of "untransformed" established cell lines. SEM can detect only the matrix stainable with the low concentration of FITC-gelatin, such as that expressed by primary chick embryo fibroblasts. The binding of fibronectin to the extracellular matrix is very stable and FITC-gelatin remained bound to the matrix for at least 10 d in culture. Radioiodinated gelatin has been used to quantitate the level of cell surface fibronectin in living normal and transformed cells. FITC-gelatin appears to be a useful probe for studying the fibronectin of living cells in culture.


2019 ◽  
Author(s):  
Shixing Ma ◽  
Aobo Zhang ◽  
Xiaole Li ◽  
Shizhou Zhang ◽  
Shaopeng Liu ◽  
...  

Abstract Background: Due to the lack of research on the pathological mechanism of temporomandibular joint osteoarthritis (TMJOA), there are few effective treatment measures in the clinic. In recent years, microRNAs (miRs) have been demonstrated to play an important role in the pathogenesis of osteoarthritis (OA) by regulating a variety of target genes, and the latest evidence shows that miR-21-5p is specifically overexpressed in OA. The purpose of this project was to clarify whether miR-21-5p can regulate the TMJOA process by targeting Spry1.Methods: TMJOA was induced by a unilateral anterior crossbite (UAC) model, and the effect of miR-21-5p knockout on TMJOA was evaluated by toluidine blue and immunohistochemical staining. Primary mouse condylar chondrocytes (MCCs) were isolated, cultured and transfected with a series of mimics, inhibitors, siRNA-Spry1 or cDNA Spry1. Western blotting, RT-qPCR, immunofluorescence staining, and toluidine blue staining were used to detect the effect of miR-21-5p and its target gene Spry1 on the expression of MMP-13, VEGF and p-ERK1/2 in TMJOA. The effect of miR-21-5p on angiogenesis was evaluated by chick embryo CAM assay and Western blotting.Results: In the UAC model, the cartilage thickness and extracellular matrix of miR-21-5p knockout mice were less damaged. Luciferase experiments confirmed that Spry1 was the direct target of miR-21-5p. The expression levels of Spry1, MMP-13, VEGF and p-ERK1/2 in MCCs transfected with miR-21-5p mimic were higher than those in the inhibitor group. Under the simulated inflammatory environment of IL-1β, the expression levels of MMP-13, VEGF and p-ERK1/2 were positively correlated with miR-21-5p, while Spry1 was negatively correlated with miR-21-5p. Inhibition of miR-21-5p expression and overexpression of Spry1 enhanced the inhibition of MMP-13, VEGF and p-ERK1/2 expression. MiR-21-5p had a significant role in promoting angiogenesis in the chick embryo CAM assay, and this role was clearly mediated by the ERK-MAPK signalling pathway.Conclusion: This study verified that miR-21-5p can promote the process of TMJOA by targeting Spry1, which provides a new direction for future research on the treatment of this disease.


1991 ◽  
Vol 99 (3) ◽  
pp. 617-626 ◽  
Author(s):  
E.J. Sanders ◽  
S. Prasad

We have examined the immunocytochemical distribution of TGF beta 1 (transforming growth factor beta 1) in the gastrulating chick embryo, and have correlated the results with the ability of this factor to promote in vitro changes in the phenotype of mesoderm and epiblast cells. The findings, together with the demonstration that exogenous TGF beta 1 is also able to modulate extracellular matrix deposition by these cells in culture, are consistent with a role for this factor in the formation and morphogenesis of the early mesoderm. Immunofluorescence analysis, using an antibody to the amino-terminal fragment of TGF beta 1, indicates that this factor is located in, or between, cells of the medial epiblast, Hensen's node and primitive streak. At Hensen's node, cells of the hypoblast were also strongly labelled. Ingressed mesoderm cells, lateral to the streak, show considerably stronger and more diffuse labelling than the overlying epiblast cells. Although the fluorescent labelling appears to be associated with the extracellular matrix surrounding the mesoderm cells, it is not bound to hyaluronic acid, which is the preponderant molecule in the matrix at this time in development. When added exogenously to cultures of mesoderm cells growing with epithelial characteristics on fibronectin, TGF beta 1 effects an epithelial-mesenchymal transformation within 24 h. The reverse transformation is effected in mesoderm cells grown on laminin, while the epiblast cell phenotype is not affected by this treatment regardless of the substratum. TGF beta 1 is also able to down-regulate the deposition of fibronectin by mesoderm cells grown on fibronectin and of epiblast cells grown on laminin, but up-regulate fibronectin deposition by mesoderm on laminin. Similar substratum-dependent changes are seen in laminin deposition, which is down-regulated in mesoderm on laminin and up-regulated in epiblast on laminin. No effect on laminin deposition is seen in either cell type grown on fibronectin. Expression of the fibronectin receptor is also down-regulated by TGF beta 1 in mesoderm cells grown on fibronectin, and this may explain the decreased deposition of fibronectin associated with these cells under these conditions. We suggest that these results are consistent with a reinforcing role for TGF beta 1 in the transformation that results in the emergence of mesoderm cells at gastrulation. This factor may also be involved in the maintenance of the fibroblastic phenotype of the mesoderm cells after their ingression, by effects on the expression of receptors for extracellular matrix and on the deposition of matrix by these cells during their early morphogenesis.


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