scholarly journals Distribution of N-CAM in synaptic and extrasynaptic portions of developing and adult skeletal muscle.

1986 ◽  
Vol 102 (3) ◽  
pp. 716-730 ◽  
Author(s):  
J Covault ◽  
J R Sanes
Keyword(s):  
Schwann Cells ◽  
Motor Nerve ◽  
Cell Types ◽  
Nerve Terminals ◽  
Electron Microscopic ◽  
Adult Skeletal Muscle ◽  
Adult Rat ◽  
Embryonic Muscle ◽  
Nerve Muscle

Previous studies of denervated and cultured muscle have shown that the expression of the neural cell adhesion molecule (N-CAM) in muscle is regulated by the muscle's state of innervation and that N-CAM might mediate some developmentally important nerve-muscle interactions. As a first step in learning whether N-CAM might regulate or be regulated by nerve-muscle interactions during normal development, we have used light and electron microscopic immunohistochemical methods to study its distribution in embryonic, perinatal, and adult rat muscle. In embryonic muscle, N-CAM is uniformly present on the surface of myotubes and in intramuscular nerves; N-CAM is also present on myoblasts, both in vivo and in cultures of embryonic muscle. N-CAM is lost from the nerves as myelination proceeds, and from myotubes as they mature. The loss of N-CAM from extrasynaptic portions of the myotube is a complex process, comprising a rapid rearrangement as secondary myotubes form, a phase of decline late in embryogenesis, a transient reappearance perinatally, and a more gradual disappearance during the first two postnatal weeks. Throughout embryonic and perinatal life, N-CAM is present at similar levels in synaptic and extrasynaptic regions of the myotube surface. However, N-CAM becomes concentrated in synaptic regions postnatally: it is present in postsynaptic and perisynaptic areas of the muscle fiber, both on the surface and intracellularly (in T-tubules), but undetectable in portions of muscle fibers distant from synapses. In addition, N-CAM is present on the surfaces of motor nerve terminals and of Schwann cells that cap nerve terminals, but absent from myelinated portions of motor axons and from myelinating Schwann cells. Thus, in the adult, N-CAM is present in synaptic but not extrasynaptic portions of all three cell types that comprise the neuromuscular junction. The times and places at which N-CAM appears are consistent with its playing several distinct roles in myogenesis, synaptogenesis, and synaptic maintenance, including alignment of secondary along primary myotubes, early interactions of axons with myotubes, and adhesion of Schwann cells to nerve terminals.

Visual identification of nerve terminals in living isolated skeletal muscle

1972 ◽  
Vol 181 (1065) ◽  
pp. 421-430 ◽  
Keyword(s):  
Electron Microscopy ◽  
Schwann Cells ◽  
Motor Nerve ◽  
Postsynaptic Membrane ◽  
Muscle Fibres ◽  
Nerve Terminals ◽  
Necturus Maculosus ◽  
Visual Identification ◽  
Collagenase Treatment ◽  
Nerve Muscle

1. The unmyelinated terminal branches of motor nerve fibres were clearly resolved in live, unstained skeletal muscles of the frog and of the mudpuppy (Necturus maculosus), using Nomarski optics. The observations were supplemented by several histological procedures, including electron microscopy, and by extracellular recordings from the nerve terminals. 2. In live motor nerve terminals of the mudpuppy one can see a series of varicosities, which in the electron microscope are shown to contain accumulations of synaptic vesicles. Junctional folds in the muscle fibres are confined to the areas opposite the varicosities. Terminal branches of the frog’s motor axon are also varicose, but the swellings are so closely spaced that they can be seen only after staining or by electron microscopy. 3. Nuclei of Schwann cells are recognized along living nerve terminals. Electrophoretic injection of a fluorescent dye, Procionyellow, into the cell bodies of Schwann cells enables one to see the distribution of their processes with the light microscope. 4. Visibility of terminal arborizations was improved by bathing nerve-muscle preparations in solutions of collagenase for 15 to 30 min, thereby removing much of the connective tissue. After longer collagenase treatment nerve terminals could be lifted off muscle fibres with a micropipette, thus exposing the postsynaptic membrane.

The neural crest population responding to endothelin-3 in vitro includes multipotent cells

1997 ◽  
Vol 110 (14) ◽  
pp. 1673-1682 ◽  
Author(s):  
J.G. Stone ◽  
L.I. Spirling ◽  
M.K. Richardson
Keyword(s):  
Neural Crest ◽  
Schwann Cells ◽  
Cell Types ◽  
Developmental Potential ◽  
Colony Assay ◽  
Cellular Targets ◽  
Multipotent Cells ◽  
Endothelin 3

The peptide endothelin 3 (EDN3) is essential for normal neural crest development in vivo, and is a potent mitogen for quail truncal crest cells in vitro. It is not known which subpopulations of crest cells are targets for this response, although it has been suggested that EDN3 is selective for melanoblasts. In the absence of cell markers for different precursor types in the quail crest, we have characterised EDN3-responsive cell types using in vitro colony assay and clonal analysis. Colonies were analysed for the presence of Schwann cells, melanocytes, adrenergic cells or sensory-like cells. We provide for the first time a description of the temporal pattern of lineage segregation in neural crest cultures. In the absence of exogenous EDN3, crest cells proliferate and then differentiate. Colony assay indicates that in these differentiated cultures few undifferentiated precursors remain and there is a low replating efficiency. By contrast, in the presence of 100 ng/ml EDN3 differentiation is inhibited and most of the cells maintain the ability to give rise to mixed colonies and clones containing neural crest derivatives. A high replating efficiency is maintained. In secondary culture there was a progressive decline in the number of cell types per colony in control medium. This loss of developmental potential was not seen when exogenous EDN3 was present. Cell type analysis suggests two novel cellular targets for EDN3 under these conditions. Contrary to expectations, one is a multipotent precursor whose descendants include melanocytes, adrenergic cells and sensory-like cells; the other can give rise to melanocytes and Schwann cells. Our data do not support previous claims that the action of EDN3 in neural crest culture is selective for cells in the melanocyte lineage.

scholarly journals The in vivo effect of lipopolysaccharide on the spontaneous release of transmitter from motor nerve terminals

1995 ◽  
Vol 116 (2) ◽  
pp. 1757-1760 ◽  
Author(s):  
Shing H. Liu ◽  
Tzong J. Sheu ◽  
Ruey H. Lin ◽  
Shoei Y. Lin-Shiau
Keyword(s):  
Motor Nerve ◽  
Nerve Terminals ◽  
Spontaneous Release ◽  
Motor Nerve Terminals

scholarly journals Glial imaging during synapse remodeling at the neuromuscular junction

2008 ◽  
Vol 4 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Yi Zuo ◽  
Derron Bishop
Keyword(s):  
Neuromuscular Junction ◽  
Schwann Cells ◽  
Synapse Formation ◽  
Ultrastructural Organization ◽  
Post Injury ◽  
Electron Microscopic ◽  
Cell Dynamics ◽  
Transmission Electron

Glia are an indispensable structural and functional component of the synapse. They modulate synaptic transmission and also play important roles in synapse formation and maintenance. The vertebrate neuromuscular junction (NMJ) is a classic model synapse. Due to its large size, simplicity and accessibility, the NMJ has contributed greatly to our understanding of synapse development and organization. In the past decade, the NMJ has also emerged as an effective model for studying glia–synapse interactions, in part due to the development of various labeling techniques that permit NMJs and associated Schwann cells (the glia at NMJs) to be visualized in vitro and in vivo. These approaches have demonstrated that Schwann cells are actively involved in synapse remodeling both during early development and in post-injury reinnervation. In vivo imaging has also recently been combined with serial section transmission electron microscopic (ssTEM) reconstruction to directly examine the ultrastructural organization of remodeling NMJs. In this review, we focus on the anatomical studies of Schwann cell dynamics and their roles in formation, maturation and remodeling of vertebrate NMJs using the highest temporal and spatial resolution methods currently available.

scholarly journals Motor Nerve Terminals As the Site of Initial Functional Changes After Denervation

1969 ◽  
Vol 53 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Michiko Okamoto ◽  
Walter F. Riker
Keyword(s):  
Motor Nerve ◽  
Repetitive Stimulation ◽  
Motor Nerve Terminal ◽  
Nerve Terminals ◽  
In Situ Experiment ◽  
Muscle System ◽  
Motor Nerve Terminals ◽  
Functional Changes ◽  
Post Tetanic Potentiation ◽  
Nerve Muscle

For the cat soleus nerve-muscle system, motor nerve section 48 hr prior to in situ experiment causes certain characteristic transmission losses. Responses to repetitive stimulation are sharply altered: The capacity to transmit iterative stimulation is severely reduced; post-tetanic potentiation and the post-tetanic repetition of soleus nerve terminals responsible for it are also greatly impaired; a phenomenon of post-tetanic depression was frequently observed. However, function of the extramuscular axons appears normal and single impulse transmission is usually not seriously affected. The loss of reactivity to repetitive stimulation has been traced to soleus motor nerve terminals. In view of these data and the known absence of denervation hypersensitivity at this time, the earliest functional failure may be said to occur in the unmyelinated terminals. This subacutely denervated preparation therefore offers a simple means of evaluating motor nerve terminal responsiveness.

scholarly journals Three-dimensional traction forces of Schwann cells on compliant substrates

2014 ◽  
Vol 11 (97) ◽  
pp. 20140247 ◽  
Author(s):  
Cristina López-Fagundo ◽  
Eyal Bar-Kochba ◽  
Liane L. Livi ◽  
Diane Hoffman-Kim ◽  
Christian Franck
Keyword(s):  
Schwann Cells ◽  
Functional Integration ◽  
Three Dimensional ◽  
Cell Types ◽  
Substrate Stiffness ◽  
Post Injury ◽  
Tissue Engineering Scaffolds ◽  
Compliant Substrates ◽  
Out Of Plane

The mechanical interaction between Schwann cells (SCs) and their microenvironment is crucial for the development, maintenance and repair of the peripheral nervous system. In this paper, we present a detailed investigation on the mechanosensitivity of SCs across a physiologically relevant substrate stiffness range. Contrary to many other cell types, we find that the SC spreading area and cytoskeletal actin architecture were relatively insensitive to substrate stiffness with pronounced stress fibre formation across all moduli tested (0.24–4.80 kPa). Consistent with the presence of stress fibres, we found that SCs generated large surface tractions on stiff substrates and large, finite material deformations on soft substrates. When quantifying the three-dimensional characteristics of the SC traction profiles, we observed a significant contribution from the out-of-plane traction component, locally giving rise to rotational moments similar to those observed in mesenchymal embryonic fibroblasts. Taken together, these measurements provide the first set of quantitative biophysical metrics of how SCs interact with their physical microenvironment, which are anticipated to aid in the development of tissue engineering scaffolds designed to promote functional integration of SCs into post-injury in vivo environments.

Blocking of frog endplate channels by the organic calcium antagonist D600

1980 ◽  
Vol 211 (1182) ◽  
pp. 15-24 ◽  
Keyword(s):  
Calcium Antagonist ◽  
Transmitter Release ◽  
Motor Nerve ◽  
Postsynaptic Membrane ◽  
Nerve Terminals ◽  
Slow Recovery ◽  
Membrane Hyperpolarization ◽  
Voltage Dependent ◽  
Nerve Muscle ◽  
Frog Sartorius

The actions of the organic ‘calcium antagonist’ D600 were examined on the frog sartorius nerve-muscle preparation. D600 blocked voltage-dependent Na + and K + membrane channels in nerve and muscle, and blocked also endplate channels induced by acetylcholine (ACh). The rate of spontaneous transmitter release from motor nerve terminals was increased by D600, independently of external Ca 2+ , although the drug had little effect on transmitter release evoked by nerve impulses. Postsynaptically, miniature endplate currents were reduced in size and their decay time constant became shorter and relatively independent of membrane potential. D600 reduced the increase in ACh-induced endplate current seen with membrane hyperpolarization, and with paired ACh pulses a marked depression and slow recovery of ACh sensitivity were observed. These actions of D600 on the postsynaptic membrane suggest that D600 may act by blocking open endplate channels.

In vivo and electron microscopic observations on Schwann cells in developing tadpole nerve fibers

1974 ◽  
Vol 141 (3) ◽  
pp. 375-391 ◽  
Author(s):  
Susan Billings-Gagliardi ◽  
Henry F. De Webster ◽  
Maureen F. O'Connell
Keyword(s):  
Schwann Cells ◽  
Nerve Fibers ◽  
Electron Microscopic

scholarly journals Molecular trapping of a fluorescent ceramide analogue at the Golgi apparatus of fixed cells: interaction with endogenous lipids provides a trans-Golgi marker for both light and electron microscopy.

1989 ◽  
Vol 109 (5) ◽  
pp. 2067-2079 ◽  
Author(s):  
R E Pagano ◽  
M A Sepanski ◽  
O C Martin
Keyword(s):  
Golgi Apparatus ◽  
Light And Electron Microscopy ◽  
Cell Types ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Fluorescent Marker ◽  
Cellular Lipids ◽  
Endogenous Lipids ◽  
Fluorescent Lipid

We have previously shown that a fluorescent derivative of ceramide, N-(epsilon-7-nitrobenz-2-oxa-1,3-diazol-4-yl-aminocaproyl)-D-eryth ro-sphingosin e (C6-NBD-Cer), vitally stains the Golgi apparatus of cells (Lipsky, N. G., and R. E. Pagano. 1985. Science (Wash. DC). 228:745-747). In the present paper we demonstrate that C6-NBD-Cer also accumulates at the Golgi apparatus of fixed cells and we explore the mechanism by which this occurs. When human skin fibroblasts were fixed with glutaraldehyde and then incubated with C6-NBD-Cer at 2 degrees C, the fluorescent lipid spontaneously transferred into the cells, labeling the Golgi apparatus as well as other intracellular membranes. Subsequent incubations with defatted BSA at 24 degrees C removed excess C6-NBD-Cer from the cells such that fluorescence was then detected only at the Golgi apparatus. Similar results were obtained using other cell types. A method for visualizing the fluorescent lipid at the electron microscopic level, based on the photoconversion of a fluorescent marker to a diaminobenzidine product (Sandell, J. H., and R. H. Masland, 1988. J. Histochem. Cytochem. 36:555-559), is described and evidence is presented that C6-NBD-Cer was localized to the trans cisternae of the Golgi apparatus. While accumulation occurred in cells fixed in various ways, it was inhibited when fixation protocols that extract or modify cellular lipids were used. In addition, Filipin, which forms complexes with cellular cholesterol, labeled the Golgi apparatus of fixed cells and inhibited accumulation of C6-NBD-Cer at the Golgi apparatus. These results are discussed in terms of a simple model based on the physical properties of C6-NBD-Cer and its interactions with endogenous lipids of the Golgi apparatus. Possible implications of these findings for metabolism and transport of (fluorescent) sphingolipids in vivo are also presented.

Sign in / Sign up

Export Citation Format

Share Document