scholarly journals Intermediate-sized filaments of the prekeratin type in myoepithelial cells.

1980 ◽  
Vol 84 (3) ◽  
pp. 633-654 ◽  
Author(s):  
W W Franke ◽  
E Schmid ◽  
C Freudenstein ◽  
B Appelhans ◽  
M Osborn ◽  
...  

Myoepithelial cells from mammary glands, the modified sweat glands of bovine muzzle, and salivary glands have been studied by electron microscopy and by immunofluorescence microscopy in frozen sections in an attempt to further characterize the type of intermediate-sized filaments present in these cells. Electron microscopy has shown that all myoepithelial cells contain extensive meshworks of intermediate-sized (7--11-nm) filaments, many of which are anchored at typical desmosomes or hemidesmosomes. The intermediate-sized filaments are also intimately associated with masses of contractile elements, identified as bundles of typical 5--6-nm microfilaments and with characteristically spaced dense bodies. This organization resembles that described for various smooth muscle cells. In immunofluorescence microscopy, using antibodies specific for the various classes of intermediate-sized filaments, the myoepithelial cells are strongly decorated by antibodies to prekeratin. They are not specifically stained by antibodies to vimentin, which stain mesenchymal cells, nor by antibodies to chick gizzard desmin, which decorate fibrils in smooth muscle Z bands and intercalated disks in skeletal and cardiac muscle of mammals. Myoepithelial cells are also strongly stained by antibodies to actin. The observations show (a) that the epithelial character, as indicated by the presence of intermediate-sized filaments of the prekeratin type, is maintained in the differentiated contractile myoepithelial cell, and (b) that desmin and desmin-containing filaments are not generally associated with musclelike cell specialization for contraction but are specific to myogenic differentiation. The data also suggest that in myoepithelial cells prekeratin filaments are arranged--and might function--in a manner similar to the desmin filaments in smooth muscle cells.

1989 ◽  
Vol 94 (4) ◽  
pp. 713-724
Author(s):  
S. Tamm ◽  
S.L. Tamm

We describe the first example of bare ciliary axonemes existing outside eukaryotic cells. The axonemes run in longitudinal invaginations of the surface membrane of giant smooth muscle cells in ctenophores. No motility of the surface-associated axonemes has been detected in living muscles. The axonemes are truly extracellular and in direct contact with the extracellular matrix (mesoglea), as shown by the ultrastructural tracer horseradish peroxidase. The axonemes appear partially degraded and disorganized, and individual doublet microtubules are difficult to distinguish. Nevertheless, immunofluorescence microscopy shows that the axonemes retain antigenic sites reacting with mouse monoclonal anti-beta-tubulin. The origin of the extracellular axonemes is unknown: no attached basal bodies (extracellular or intracellular) have been found. The muscle-associated axonemes may play a unique role in smooth muscle function and/or development, and may be related to the evolution of muscle cells in soft-bodied invertebrates that exploit cilia for a wide variety of functions.


2018 ◽  
Vol 33 (4) ◽  
pp. 416-425 ◽  
Author(s):  
Jia Yan ◽  
Kun Hu ◽  
YongHao Xiao ◽  
Fan Zhang ◽  
Lu Han ◽  
...  

A novel recombinant human-like collagen/fibroin scaffold has been prepared previously, which has high porosity, controllable pore size, and much better mechanical properties than the reported fibroin-based scaffold. In this research, the cell responses of vascular smooth muscle cells to this blend scaffold were examined in vitro. Cell morphology, adherence, and growth in scaffolds were observed by scanning electron microscopy, laser scanning confocal microscopy after staining of the cells with propidium iodide at 1, 3, 5, and 7 days, respectively. A wide range of measurements, including 3-[4,5–dimethylthiazol-2-yl]-2, 5-diphenyl tetrasodium bromide assay, and total intracellular protein content at the end of 7 days culture, were conducted. An increase of viability and protein content of vascular smooth muscle cells cultured in recombinant human-like collagen/fibroin scaffold was found. The laser scanning confocal microscopy and scanning electron microscopy results confirm that the cells readily adhered and proliferation in the blend than in fibroin scaffold, and indicate a better adhesion process. The positive effects were especially significant for vascular smooth muscle cells. The recombinant human-like collagen/fibroin scaffold could be a promising biomaterial for vascular tissue engineering.


1971 ◽  
Vol 49 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Gordon R. Campbell ◽  
Yasuo Uehara ◽  
Gerda Mark ◽  
Geoffrey Burnstock

The fine structure of smooth muscle cells of the embryo chicken gizzard cultured in monolayer was studied by phase-contrast optics and electron microscopy. The smooth muscle cells were irregular in shape, but tended to be elongate. The nucleus usually contained prominent nucleoli and was large in relation to the cell body. When fixed with glutaraldehyde, three different types of filaments were noted in the cytoplasm: thick (150–250 A in diameter) and thin (30–80 A in diameter) myofilaments, many of which were arranged in small bundles throughout the cytoplasm and which were usually associated with dark bodies; and filaments with a diameter of 80–110 A which were randomly orientated and are not regarded as myofilaments. Some of the aggregated ribosomes were helically arranged. Mitochondria, Golgi apparatus, and dilated rough endoplasmic reticulum were prominent. In contrast to in vivo muscle cells, micropinocytotic vesicles along the cell membrane were rare and dense areas were usually confined to cell membrane infoldings. These cells are compared to in vivo embryonic smooth muscle and adult muscle after treatment with estrogen. Monolayers of cultured smooth muscle will be of particular value in relating ultrastructural features to functional observations on the same cells.


2021 ◽  
Author(s):  
Xuling Lv ◽  
Hao Chen ◽  
Zikai Zhang ◽  
Tian Li ◽  
Qing Wei ◽  
...  

Abstract Background: Pelvic floor dysfunction (PFD) is a spectrum of disorders including stress urinary incontinence and pelvic organ prolapse. Transforming growth factor-β1 (TGF-β1) can induce mesenchymal stem cells (MSCs) to differentiate into smooth muscle cells (SMCs). SMCs derived from adipose-derived stem cells (ADSCs) can be used to repair damaged pelvic floor smooth muscle tissues, which is of great interest for clinical applications using stem cell therapy for PFD. The Wnt/β-catenin pathway acts as a decisive factor in the fate of stem cells.Methods and Results: In this study, we used medium containing TGF-β1, TGF-β1 inhibitor LY2109761, or Wnt/β-catenin inhibitor KYA1797K, to induce ADCSs to differentiate into SMCs in vitro to explore the influence of TGF-β1 on the myogenic differentiation of ADCSs via the Wnt/β-catenin pathway. Results: 1) TGF-β1 induces ADSC-derived SMCs to hyper-express the SMC markers including SMA-α, Desmin, Calponin, and SMMHC ; 2) TGF-β1 activates the Wnt/β-catenin signaling pathway in ADSCs. After blocking TGF-β1, the Wnt/β-catenin pathway and myogenic differentiation in cells were inhibited; 3) the Wnt/β-catenin pathway is involved in the differentiation of ADSCs into SMCs. After differentiation induction, the synchronized changes in the activation of Wnt/β-catenin signaling and the expression of SMC-specific proteins showed a trend of simultaneous changes, and after the inhibition of the Wnt pathway, the adult muscle differentiation was significantly inhibited.Conclusions: We established a simpler and more efficient method for inducing ADSCs to differentiate into SMCs using TGF-β1 and demonstrated that the Wnt/β-catenin signaling pathway is activated during this process.


2003 ◽  
Vol 285 (5) ◽  
pp. C1330-C1338 ◽  
Author(s):  
M. Sajid ◽  
R. Zhao ◽  
A. Pathak ◽  
S. S. Smyth ◽  
G. A. Stouffer

αvβ3-Integrin antagonists reduced neointimal formation following vascular injury in eight different animal models. Because α-thrombin contributes to neointimal formation, we examined the hypothesis that αvβ3-integrins influence α-thrombin-induced signaling. Cultured rat aortic smooth muscle cells (RASMC) expressed αvβ3-integrins as demonstrated by immunofluorescence microscopy and fluorescence-activated cell sorting analysis. Proliferative responses to α-thrombin were partially inhibited by anti-β3-integrin monoclonal antibody F11 and by cyclic RGD peptides. Immunofluorescence microscopy showed that α-thrombin stimulated a rapid increase in the formation of focal adhesions as identified by vinculin staining and that this effect was partially inhibited by αvβ3 antagonists. β3-Integrin staining was diffuse in quiescent RASMC and did not concentrate at sites of focal adhesions following thrombin treatment. α-Thrombin elicited a time-dependent increase in activation of c-Jun NH2-terminal kinase-1 (JNK1) and in tyrosine phosphorylation of focal adhesion kinase (FAK). αvβ3-Integrin antagonists partially inhibited increases in JNK1 activity but had no effect on FAK phosphorylation. In SMC isolated from β3-integrin-deficient mice, focal adhesion formation was impaired in response to thrombin but not sphingosine-1-phosphate, a potent activator of Rho. In summary, αvβ3-integrins play an important role in α-thrombin-induced proliferation and focal adhesion formation in RASMC.


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