Structure and mechanics of starfish body wall

1989 ◽  
Vol 147 (1) ◽  
pp. 53-89 ◽  
Author(s):  
P. O'Neill
Keyword(s):  
Stress Relaxation ◽  
Neural Control ◽  
Body Wall ◽  
Three Dimensional ◽  
Polarized Light ◽  
The Body ◽  
Strain Rates ◽  
Collagen Fibres ◽  
Young’S Moduli ◽  
Tension Tests

The structure of the dorsal body wall of the starfish Echinaster spinulosus was studied using polarized light microscopy of frozen tissues, scanning electron microscopy and histology. The collagen fibres of the body wall form a three-dimensional orthogonal web. Voids in the web contain ossicles and papulae. The orthogonal web delivers dimensional stability but allows shear necessary for ray torsion. The ossicles and fibres interact to load the fibres in tension and the ossicles in compression. Strain rates of the dorsal body wall were measured on live animals during typical movements. Uniaxial tension tests of the body wall yielded Young's moduli of 267 MPa (longitudinal), 249 MPa (transverse) and 353 MPa (bias); curves were essentially linear. The body wall was approximately linearly viscoelastic and showed hysteresis at 0.01 Hz. Stress relaxation over five decades of time (in seconds) yielded relaxation spectra with peaks in relaxation time at 2.96-3.35, depending on test direction. Stress relaxation caused the connective tissue to soften. The surface of fractured stress-relaxed tissue revealed wispy, dissociated fibril tufts, whereas unrelaxed fractures produced blunt-ended fibre bundles. Neural control was necessary for body wall integrity.

Mechanical Diversity of Connective Tissue of the Body Wall of Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 107-125
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Connective Tissue ◽  
Body Wall ◽  
Polarized Light ◽  
Structural Features ◽  
Mechanical Tests ◽  
The Body ◽  
Sea Anemones ◽  
Collagen Fibres ◽  
Postural Changes ◽  
Anthopleura Xanthogrammica

Techniques for analysing polymer mechanics were used to describe quantitatively the time-dependent mechanical properties of the body-wall connective tissue (mesogloea) and to indicate macromolecular mechanisms responsible for the mechanical behaviour of two species of sea anemones, Metridium senile and Anthopleura xanthogrammica. 1. The mesogloea of M. senile is more extensible and less resilient than that of A. xanthogrammica when stressed for periods comparable to the duration of flow forces the anemones encounter and the postural changes they perform.2. Polarized light microscopy and SEM reveal that the reinforcing collagen fibres in the mesogloea are aligned parallel with the major stress axes in the body wall.3. Mechanical tests and observations of composition and microstructure indicate that the mesogloea of A. xanthogrammica is less extensible than that of M. senile because molecular entanglements (due to more closely packed parallel collagen fibres and to a higher concentration of polymers in the interfibrillar matrix) retard the extension of A. xanthogrammica mesogloea. This study illustrates how structural features on the macromolecular and microscopic levels of organization of an organism can equip that organism for the particular mechanical activities it performs and the environmental forces it encounters.

scholarly journals Three-dimensional simulation of the Caenorhabditis elegans body and muscle cells in liquid and gel environments for behavioural analysis

2018 ◽  
Vol 373 (1758) ◽  
pp. 20170376 ◽  
Author(s):  
Andrey Palyanov ◽  
Sergey Khayrulin ◽  
Stephen D. Larson
Keyword(s):  
Caenorhabditis Elegans ◽  
Muscle Activation ◽  
Body Wall ◽  
Particle System ◽  
Three Dimensional ◽  
Muscle Cells ◽  
The Body ◽  
C Elegans ◽  
Muscle Activation Patterns ◽  
Simulation Engine

To better understand how a nervous system controls the movements of an organism, we have created a three-dimensional computational biomechanical model of the Caenorhabditis elegans body based on real anatomical structure. The body model is created with a particle system–based simulation engine known as Sibernetic, which implements the smoothed particle–hydrodynamics algorithm. The model includes an elastic body-wall cuticle subject to hydrostatic pressure. This cuticle is then driven by body-wall muscle cells that contract and relax, whose positions and shape are mapped from C. elegans anatomy, and determined from light microscopy and electron micrograph data. We show that by using different muscle activation patterns, this model is capable of producing C. elegans -like behaviours, including crawling and swimming locomotion in environments with different viscosities, while fitting multiple additional known biomechanical properties of the animal.  This article is part of a discussion meeting issue ‘Connectome to behaviour: modelling C. elegans at cellular resolution’.

scholarly journals Three-dimensional mobility and muscle attachments in the pectoral limb of the Triassic cynodontMassetognathus pascuali

2017 ◽  
Author(s):  
Phil H. Lai ◽  
Andrew A. Biewener ◽  
Stephanie E. Pierce
Keyword(s):  
Body Wall ◽  
Three Dimensional ◽  
Detailed Examination ◽  
The Body ◽  
Three Dimensions ◽  
Glenoid Fossa ◽  
Micro Computed Tomography ◽  
Skeletal Morphology ◽  
Shoulder Muscles ◽  
Maximum Range

ABSTRACTThe musculoskeletal configuration of the mammalian pectoral limb has been heralded as a key anatomical feature leading to the adaptive radiation of mammals, but limb function in the cynodont outgroup remains unresolved. Conflicting reconstructions of abducted and adducted posture are based on mutually-incompatible interpretations of ambiguous osteology. We reconstruct the pectoral limb of the Triassic non-mammalian cynodontMassetognathus pascualiin three dimensions, by combining skeletal morphology from micro-computed tomography with muscle anatomy from an extended extant phylogenetic bracket. Conservative tests of maximum range of motion suggest a degree of girdle mobility, as well as substantial freedom at the shoulder and the elbow joints. The glenoid fossa supports a neutral pose in which the distal end of the humerus points 45° posterolaterally from the body wall, intermediate between classically “sprawling” and “parasagittal” limb postures.Massetognathusis reconstructed as having a near-mammalian complement of shoulder muscles, including an incipient rotator cuff (m. subscapularis, m. infraspinatus, m. supraspinatus, and m. teres minor). Based on close inspection of the morphology of the glenoid fossa, we hypothesize a posture-driven scenario for the evolution of the therian ball-and-socket shoulder joint. The musculoskeletal reconstruction presented here provides the anatomical scaffolding for more detailed examination of locomotor evolution in the precursors to mammals.

Anatomy of the intestine of Ascaris suum: a three dimensional study with silicone rubber casts

1977 ◽  
Vol 55 (7) ◽  
pp. 1110-1117
Author(s):  
Robert P. Harpur
Keyword(s):  
Body Wall ◽  
Female Worm ◽  
Ascaris Suum ◽  
Three Dimensional ◽  
Cross Sectional Area ◽  
The Body ◽  
Sectional Area ◽  
Expansion Chamber ◽  
Cross Sectional ◽  
Posterior Intestine

To facilitate studies of the physiology of Ascaris suum the relations between the intestine and the other organs were investigated. The anterior intestine, which starts, with a thin-walled expansion chamber, is held by connective tissue and by the bellies of muscle cells. A coarctation of the intestine marks the junction of the anterior and midintestine and in the female this narrowing occurs near the genital pore. The midintestine lies free amongst the reproductive organs and terminates near the most posterior excursions of the ovaries and uteri in the female, and of the testis in the male. The posterior intestine is attached continuously, but not initially circumferentially, to the body wall. Relative lengths for the different parts of the female worm are given and microfil casts made in situ with both sexes yielded information about the relative volumes of the midintestine and posterior intestine. The coarctation is the narrowest pan of the intestine and the largest cross-sectional area is reached at the start of the posterior intestine. The attachments to the body wall indicate that the anterior and posterior intestine change length like an accordion when the muscles contract but the cross-sectional area of the lumen is decreased by dorsoventral compression.

Scanning Electron Microscopy of the Male Nematode Physaloptera (Tetradelphynema)

1977 ◽  
Vol 35 ◽  
pp. 674-675 ◽  
Author(s):  
Bahja I. Behbehani ◽  
Ramesh K. Nayak ◽  
Randall E. McCoy
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Body Wall ◽  
Three Dimensional ◽  
Ultrastructural Level ◽  
The Body ◽  
Buffer Solution ◽  
Surface Features ◽  
Cacodylate Buffer ◽  
Scanning Electron

Nematodes are elongate, unsegmented worms with an elastic cuticle made of protein. Few published references concerning scanning electron microscopy of nematode are available and there is paucity of information at the ultrastructural level on cuticle forming male reproductive structures. The species of the genus Physaloptera (tetradelphynema) commonly live as parasites in the adult form in the stomach of the desert rodent Gerbillus cheesmani. To date, the three-dimensional surface features of this spiruroid nematode have not been described. The main purpose of this investigation was to elucidate the surface features of the male nematode utilizing the current techniques of scanning electron microscopy.Adult worms were collected in the laboratory from the stomach of the gerbil, Gerbillus cheesmani. They were washed in PO4 buffer solution and subsequently fixed overnight in 2.5% glutaraldehyde in 0.1 M cacodylate buffer. Following fixation, the specimens were washed 3 times in buffer and sonically cleaned for 30 seconds to remove debris adhering on the body wall of the nematode.

scholarly journals Direct Peristaltic Progression and the Functional Significance of the Dermal Connective Tissues During Burrowing in the Polychaete Polyphysia Crassa (Oersted)

1973 ◽  
Vol 58 (3) ◽  
pp. 637-655
Author(s):  
HUGH Y. ELDER
Keyword(s):  
Body Wall ◽  
Applied Pressure ◽  
Three Dimensional ◽  
Collagen Fibre ◽  
Elastic Fibre ◽  
The Body ◽  
Coelomic Fluid ◽  
Fourfold Increase ◽  
Burrow Wall ◽  
Dermal Collagen

1. Polyphysia excavates its burrow in soft, sublittoral mud by sinusoidal waves of the septate anterior region of the body and the lateral scraping action of the prostomial horns. 2. Associated with discrete, direct peristaltic constrictions, in which the longitudinal muscles shorten to 40%, and the circulars to 80%, of their distended lengths, hydraulic deployment of coelomic fluid converts the periodic advance of the trunk segments into continuous head progression. 3. Direct peristaltic progression advances the body by one-fifth or less of a wavelength per cycle, which is comparable to the figure for earthworm locomotion. 4. A three-dimensional dermal collagen fibre lattice accommodates extensive folding of the cuticle and epidermis while permitting a three- to fourfold increase in the radial dimension of the body wall during peristaltic constriction. Elastic fibre columns oppose the radial distension and control the cuticular folding. 5. These features are seen as adaptations to burrowing in the soft mud habitat. The high degree of body-wall flexibility permits the transition from contracted to distended configuration within the length of one segment. Some three-quarters of the body surface may be in contact with the burrow wall at any one time. Unlike other soft-bodied burrowing animals the force exerted on the burrow wall is unidirectional and the applied pressure is probably small, relatively constant and spread over a wide area.

Electron Microscope and Histochemical Observations on the Daughter Sporocyst of Schistosoma mattheei and Schistosoma bovis

1971 ◽  
Vol 45 (2-3) ◽  
pp. 237-244 ◽  
Author(s):  
G. K. Kinoti ◽  
R. G. Bird ◽  
Mary Barker
Keyword(s):  
Electron Microscopy ◽  
Alkaline Phosphatase ◽  
Body Wall ◽  
The Body ◽  
Active Process ◽  
Collagen Fibres ◽  
Daughter Sporocyst ◽  
Schistosoma Bovis ◽  
Electron Microscopical ◽  
Snail Tissue

Electron-microscopical, histological and histochemical observations were carried out on the body wall of the daughter sporocyst stage of Schistosoma mattheei and S. bovis. Electron microscopy revealed that the body wall consists of a continuous outer layer of cytoplasm, collagen fibres, fibroblasts and a layer of somatic cells which are apparently continuous with the cytoplasmic layer. This layer forms numerous microvilli at the surface.Pronounced alkaline phosphatase activity was found in the sporocyst body wall, but no evidence of esterases was found in the parasite although esterase activity was readily demonstrated in the snail tissue that the schistosome parasitized.It is concluded that the passage of substances such as glucose across the surface of the sporocyst is an active process probably mediated by enzymes and that little, if any, lipid metabolism occurs in the sporocyst stage.

Scanning electron microscopy of freeze-fractured prescapular lymph node of caprine

1984 ◽  
Vol 42 ◽  
pp. 244-245
Author(s):  
O. Faroon ◽  
F. Al-Bagdadi ◽  
T. G. Snider ◽  
C. Titkemeyer
Keyword(s):  
Lymph Node ◽  
Lymph Nodes ◽  
Lymphatic System ◽  
Three Dimensional ◽  
Meat Products ◽  
The Body ◽  
Morphological Data ◽  
The World ◽  
Cellular Constituent ◽  
Scanning Electron

The lymphatic system is very important in the immunological activities of the body. Clinicians confirm the diagnosis of infectious diseases by palpating the involved cutaneous lymph node for changes in size, heat, and consistency. Clinical pathologists diagnose systemic diseases through biopsies of superficial lymph nodes. In many parts of the world the goat is considered as an important source of milk and meat products.The lymphatic system has been studied extensively. These studies lack precise information on the natural morphology of the lymph nodes and their vascular and cellular constituent. This is due to using improper technique for such studies. A few studies used the SEM, conducted by cutting the lymph node with a blade. The morphological data collected by this method are artificial and do not reflect the normal three dimensional surface of the examined area of the lymph node. SEM has been used to study the lymph vessels and lymph nodes of different animals. No information on the cutaneous lymph nodes of the goat has ever been collected using the scanning electron microscope.

Lymphangiomatosis of the Body Wall: A Report of Two Cases Associated with Chylothorax and Fatal Outcome

1997 ◽  
Vol 17 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Philippe Moerman ◽  
Chris Van Geet ◽  
Hugo Devlieger
Keyword(s):  
Body Wall ◽  
Fatal Outcome ◽  
The Body

scholarly journals Mass-resolved electronic circular dichroism ion spectroscopy

Science ◽  
2020 ◽  
Vol 368 (6498) ◽  
pp. 1465-1468 ◽  
Author(s):  
Steven Daly ◽  
Frédéric Rosu ◽  
Valérie Gabelica
Keyword(s):  
Circular Dichroism ◽  
Three Dimensional ◽  
Polarized Light ◽  
Negative Ions ◽  
Data Interpretation ◽  
Electronic Circular Dichroism ◽  
Circularly Polarized Light ◽  
Chiral Compounds ◽  
Electron Photodetachment ◽  
Circular Dichroïsm

DNA and proteins are chiral: Their three-dimensional structures cannot be superimposed with their mirror images. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with an ultraviolet nanosecond optical parametric oscillator laser, and measured the difference in electron photodetachment efficiency between left and right circularly polarized light. The reconstructed circular dichroism ion spectra resembled those of their solution-phase counterparts, thereby allowing us to assign the DNA helical topology. The ability to measure circular dichroism directly on biomolecular ions expands the capabilities of mass spectrometry for structural analysis.

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