The innervation of the ampulla of the tube foot in the starfish Astropecten irregularis

1967 ◽  
Vol 168 (1010) ◽  
pp. 91-99 ◽  
Keyword(s):  
Methylene Blue ◽  
Electron Microscope ◽  
Neuromuscular Junctions ◽  
Muscle Cells ◽  
Central Core ◽  
Muscle Fibres ◽  
Nerve Fibres ◽  
Clear Cytoplasm ◽  
Tube Feet

In the ampullae of the starfish Astropecten irregularis extensions stretch from the main soma of the muscle cells down the seams of the ampullae into bulbs of tissue in the tube feet. Their terminations range from 0.2 to 4.0 μm in diameter. Here axons in tracts from the radial cord form synapses upon the extensions of the muscle cells. In sections examined with the electron microscope the extensions are distinguished from nerves by their central core of myofilaments, surrounded by clear cytoplasm. The junctions between the extensions of the muscle cells and the nerve fibres show no peculiarities of the membrane and are recognized as synapses only by their vesicles. No nerve fibres or neuromuscular junctions can be identified in the ampulla, and structures described from material vitally stained with methylene blue must be reinterpreted. The fibres which run along the seam of the ampullae, formerly described as axons, are extensions of muscle cells, to which they can be traced. The muscle fibres of the ampullae have large fluid-filled spaces around the myofilaments and it is proposed that some stain selectively and give rise to the structures originally described as ribbon axons.

Non-motile sensory cilia and neuromuscular junctions in a ctenophore independent effector organ

1965 ◽  
Vol 162 (988) ◽  
pp. 333-350 ◽  
Keyword(s):  
Neuromuscular Junctions ◽  
Ciliated Cell ◽  
Sensory Nerve ◽  
Spatial Summation ◽  
Muscle Cells ◽  
Sensory Cells ◽  
Muscle Fibres ◽  
Water Displacement ◽  
Single Finger ◽  
Effector Organ

Non-motile cilia of the (9 + 2) pattern, having a specialized onion-like root structure, act as sensitive receptors of water displacement and thereby detect vibrations of small objects in the water nearby. These receptors are situated on sensory nerve cells on finger-like processes up to 1 cm long, on the surface of the ctenophore Leucothea ( = Eucharis) multicornis . In response to vibration a single finger can shoot outwards as an independent effector by an extension of its mesogloeal hydrostatic skeleton, acted on by circular and transverse muscle fibres which run mainly through the mesogloea. A copepod which may be hit is immobilized, presumably by a poisonous secretion. Retraction is brought about by longitudinal ectodermal fibres. The neuromuscular junctions have presynaptic vesicles of 30 to 50 nm diameter, a cleft of 15 to 20 nm wide, and occur at discrete points far from each other on the muscle cells, suggesting that excitation is propagated along the muscle fibres. No direct connexion has been traced between a sensory ciliated cell and a muscle fibre, but sensory cells connect with nerve net neurons and these form synapses with each other and with muscle cells. There are numerous nerve fibres in the epithelium and synapses with vesicles on one side of a cleft 12 to 15 nm wide occur between them sufficiently closely for spatial summation to be possible. The separate co-ordination of movements of extension, retraction and bending requires that certain types of sensory cells be connected specifically, if in directly, with muscle fibres of a particular directionality. This provides a primitive example of specificity of connexions which must imply two overlapping nerve nets.

A note on the structure of immunized endplates

1977 ◽  
Vol 195 (1119) ◽  
pp. 323-326
Keyword(s):  
Electron Microscope ◽  
Acetylcholine Receptors ◽  
Neuromuscular Transmission ◽  
Neuromuscular Junctions ◽  
Muscle Membrane ◽  
Muscle Fibres

Neuromuscular junctions of rabbits immunized against acetylcholine receptors were examined with the electron microscope. Many endplates appeared normal, or showed changes which, by themselves, would not account for the blockage of neuromuscular transmission which develops after immunization. An unexpected organelle was found in the muscle fibres, associated with the endplate nuclei and the cytoplasm between them and the synaptic muscle membrane.

Influence of Temperature on the Transmembrane Potential of Ascaris Muscle Cells

1968 ◽  
Vol 48 (2) ◽  
pp. 405-410
Author(s):  
JEAN T. DEBELL ◽  
V. SANCHEZ
Keyword(s):  
Inverse Relationship ◽  
Transmembrane Potential ◽  
Neuromuscular Junctions ◽  
Thermal Sensitivity ◽  
Muscle Cells ◽  
Bath Temperature ◽  
Nerve Fibres ◽  
Somatic Muscle ◽  
Thermal Changes ◽  
Influence Of Temperature On

1. It has been shown that there is an almost linear inverse relationship between the transmembrane potential of the somatic muscle cells of Ascaris lumbricoides and the bath temperature between 38° and 20° C. 2. It has also been shown that the spike frequency reflects these changes, decreasing at a rate of 0.6 impulse/sec./mV. 3. D-Tubocurarine interferes with the response of these cells to thermal changes between 380 and 20° C. but it is ineffective below 20° C. 4. It is proposed that the presynaptic nerve fibres are responsible for the thermal sensitivity of the muscle cells, since the amount of depolarizing neurohormone spontaneously released at the neuromuscular junctions would depend upon the temperature.

Multinucleation during myogenesis of the myotome of Xenopus laevis: a qualitative study

Development ◽  
1987 ◽  
Vol 101 (3) ◽  
pp. 583-590 ◽  
Author(s):  
H. Boudjelida ◽  
L. Muntz
Keyword(s):  
Electron Microscope ◽  
Qualitative Study ◽  
Xenopus Laevis ◽  
Dna Synthesis ◽  
Satellite Cells ◽  
Muscle Cells ◽  
Muscle Fibres ◽  
Large Nucleus ◽  
Ultrastructural Studies

Ultrastructural studies of myogenesis in the myotome of Xenopus laevis reveal that the myotubes developed by stage 33/34 have peripheral myofibrils but are still uninucleate with a single large nucleus. By stage 45, the cytoplasm of the muscle cells is filled with myofibrils and there are many small peripheral nuclei, resulting in multinucleate muscle fibres. With the electron microscope, we have examined myotomes from stages 33/34 to 59 of development and some stages were also investigated by autoradiography. There was no evidence from autoradiographic studies for DNA synthesis in muscle cells, and the increase in the number of myonuclei was accompanied by a decrease in their size. Satellite cells were not seen at the myotube stage but were first seen after the cells had become multinucleate, with many small nuclei close together forming rows. Constrictions were frequently observed in the large single nuclei. It is concluded that division of the myonuclei by amitosis is mainly responsible for the multinucleation that occurs during development of the myotome muscle in Xenopus laevis.

scholarly journals Effective Magnetic MOFs Adsorbent for the Removal of Bisphenol A, Tetracycline, Congo Red and Methylene Blue Pollutions

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1917
Author(s):  
Guangpu Zhang ◽  
Rong Wo ◽  
Zhe Sun ◽  
Gazi Hao ◽  
Guigao Liu ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Electron Microscope ◽  
Bisphenol A ◽  
Congo Red ◽  
Reduction Process ◽  
Entropy Change ◽  
Potential Candidate ◽  
Order Kinetic ◽  
Adsorption Processes ◽  
Infrared Spectrometer

A magnetic metal−organic frameworks adsorbent (Fe3O4@MIL-53(Al)) was prepared by a typical solvothermal method for the removal of bisphenol A (BPA), tetracycline (TC), congo red (CR), and methylene blue (MB). The prepared Fe3O4@MIL-53(Al) composite adsorbent was well characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and fourier transform infrared spectrometer (FTIR). The influence of adsorbent quantity, adsorption time, pH and ionic strength on the adsorption of the mentioned pollutants were also studied by a UV/Vis spectrophotometer. The adsorption capacities were found to be 160.9 mg/g for BPA, 47.8 mg/g for TC, 234.4 mg/g for CR, 70.8 mg/g for MB, respectively, which is superior to the other reported adsorbents. The adsorption of BPA, TC, and CR were well-fitted by the Langmuir adsorption isotherm model, while MB followed the Freundlich model, while the adsorption kinetics data of all pollutants followed the pseudo-second-order kinetic models. The thermodynamic values, including the enthalpy change (ΔH°), the Gibbs free energy change (ΔG°), and entropy change (ΔS°), showed that the adsorption processes were spontaneous and exothermic entropy-reduction process for BPA, but spontaneous and endothermic entropy-increasing processes for the others. The Fe3O4@MIL-53(Al) was also found to be easily separated after external magnetic field, can be a potential candidate for future water treatment.

scholarly journals Association of beta-cytoplasmic actin with high concentrations of acetylcholine receptor (AChR) in normal and anti-AChR-treated primary rat muscle cultures.

1984 ◽  
Vol 32 (9) ◽  
pp. 973-981 ◽  
Author(s):  
B W Lubit
Keyword(s):  
Acetylcholine Receptor ◽  
Acetylcholine Receptors ◽  
Neuromuscular Junctions ◽  
Morphological Changes ◽  
Muscle Cells ◽  
High Concentration ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
High Concentrations

Previous immunocytochemical studies in which an antibody specific for mammalian cytoplasmic actin was used showed that a high concentration of cytoplasmic actin exists at neuromuscular junctions of rat muscle fibers such that the distribution of actin corresponded exactly to that of the acetylcholine receptors. Although clusters of acetylcholine receptors also are present in noninnervated rat and chick muscle cells grown in vitro, neither the mechanism for the formation and maintenance of these clusters nor the relationship of these clusters to the high density of acetylcholine receptors at the neuromuscular junction in vivo are known. In the present study, a relationship between beta-cytoplasmic actin and acetylcholine receptors in vitro has been demonstrated immunocytochemically using an antibody specific for the beta-form of cytoplasmic actin. Networks of cytoplasmic actin-containing filaments were found in discrete regions of the myotube membrane that also contained high concentrations of acetylcholine receptors; such high concentrations of acetylcholine receptors have been described in regions of membrane-substrate contact. Moreover, when primary rat myotubes were exposed to human myasthenic serum, gross morphological changes, accompanied by an apparent rearrangement of the cytoplasmic actin-containing cytoskeleton, were produced. Although whether the distribution of cytoplasmic actin-containing structures was influenced by the organization of acetylcholine receptor or vice versa cannot be determined from these studies, these findings suggest that in primary rat muscle cells grown in vitro, acetylcholine receptors and beta-cytoplasmic actin-containing structures may be somehow connected.

Toward standards in practices and techniques on ootaxonomy in the Pieridae (Lepidoptera: Papilionoidea)

Zootaxa ◽  
2021 ◽  
Vol 4985 (3) ◽  
Author(s):  
SANDRA NIEVES-URIBE ◽  
JORGE LLORENTE-BOUSQUETS ◽  
ADRIÁN FLORES-GALLARDO
Keyword(s):  
Methylene Blue ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Graphic Representation ◽  
Blue Staining ◽  
Detailed Data ◽  
Staining Techniques ◽  
General Aspects ◽  
Scanning Electron

We present a proposal on the standards used on ootaxonomy practices and techniques in the butterfly family Pieridae Duponchel (Lepidoptera: Papilionoidea) in five stages: 1) getting the specimens, 2) integration into a collection, 3) dissections to recover the exochorion, 4) elaboration of images of it, and 5) the preparation of its description with the necessary diagrams and tabulations. Also, we present the detailed techniques applied in observation and graphic representation, based on the methylene blue staining techniques and those required for the use with the scanning electron microscope (SEM). We compare the result of the standardized techniques with those from macro photography, drawings, and photographs with SEM—all of them found in books with descriptions and images of eggs of the Pieridae. We present a glossary and general aspects of the exochorion in the Pieridae as an Appendix to this article. Standardized techniques show more accurate and extensive character retrieval for systematics. For the scale in which they work, these techniques recovered more information than those present from oviposited eggs, where the exochorionic base is not seen. Also, the descriptions contain detailed data on more structures—which are comparable to each other—than are absent in the references mentioned. We present the recovered characters with the techniques found in the literature as three synthetically supplementary materials.

The Ultra-fine Structure of Lipid Globules in the Neurones of Helix aspersa

1958 ◽  
Vol s3-99 (46) ◽  
pp. 279-284
Author(s):  
J.T. Y. CHOU ◽  
G. A. MEEK
Keyword(s):  
Methylene Blue ◽  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Helix Aspersa

The three kinds of lipid globules recognizable in the living neurones of Helix aspersa have been examined under the electron microscope. The globules of the kind that can be stained blue with methylene blue during life are seen in electron micrographs as spheres or spheroids, with concentric lamination, after calcium-osmium fixation. After fixation with sucrose-osmium laminated crescentic bodies are seen instead; these appear to be formed by distortion of the ‘blue’ globules. The yellow globules contain electrondense material, and sometimes appear reticular. It is possible that the yellow globules may originate by transformation of some of the ‘blue’ globules. The colourless globules generally appear as crenated objects; this appearance may be a shrinkage artifact. Apart from the mitochondria and the three kinds of lipid globules described, no other object large enough to be identified with the light microscope has been seen in the cytoplasm.

scholarly journals AN ELECTRON MICROSCOPE STUDY OF THE EMBRYOLOGY OF THE INTERCALATED DISC IN THE HEART OF THE RABBIT

1957 ◽  
Vol 3 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Alan R. Muir
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Cardiac Muscle ◽  
Microscope Study ◽  
Light Microscope ◽  
Electron Microscope Study ◽  
Muscle Cells ◽  
Intercalated Disc ◽  
Adult Cell ◽  
Embryonic Muscle

Prenatal and postnatal cardiac muscle from rabbits has been studied by electron microscopy, after osmium fixation and methacrylate embedding. The observations showed that 1. Cell membranes divide the muscle into cellular units from the youngest embryo which was studied (9½ days after coitus) until the adult state. 2. The embryonic muscle cells contain only one nucleus, whereas the adult cell may be multinucleated. 3. At all stages of development, wherever a myofibrillar axis crosses a cellular boundary, the myofilaments are interrupted by an intercalated disc. 4. With age, increase in size and complexity of the discs render them recognisable by the light microscope.

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