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.

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.

Viso-Elastic Properties of the Body-Wall of Sea Anemones

1962 ◽  
Vol 39 (3) ◽  
pp. 373-386
Author(s):  
R. MCN. ALEXANDER
Keyword(s):  
Tensile Stress ◽  
Elastic Properties ◽  
Body Wall ◽  
The Body ◽  
Polymeric System ◽  
Retardation Time ◽  
Sea Anemones

1. Creep of narcotized Metridium and Calliactis body-wall at constant tensile stress has been studied quantitatively. 2. It was found to be reversible, and seemed to be controlled by the mesogloea. Its course could be represented by equations of the formε(t)= εo+ευ(I-e-t/τ),where the retardation time τ was about 1 hr. for Metridium and many hours for Calliactis. 3. The results can most simply be explained in terms of a cross-linked and a noncross-linked polymeric system, acting in parallel. An explanation in terms of a lattice of inextensible fibres is not satisfactory. 4. The results are discussed in relation to the behaviour of the animals.

Mechanical Organization of Cantileverlike Sessile Organisms: Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 127-142
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Elastic Modulus ◽  
Body Wall ◽  
Local Buckling ◽  
Beam Theory ◽  
Extension Rate ◽  
Flexural Stiffness ◽  
Sea Anemones ◽  
Order Of Magnitude ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Engineering beam theory has been used to analyse the ways in which body shape and elastic modulus of two species of sea anemones affect their mechanical responses to flow. 1.Anthopleura xanthogrammica is exposed to wave action, but because it is short, wide, and thick-walled, maximum tensile stresses in its body walls due to flow forces are an order of magnitude lower than those in the tall, slim, thin-walled, calm-water sea anemone Metridium senile.2. The elastic modulus of M. senile body wall is more dependent on extension rate than is that of A. xanthogrammica. Because the extension rate of M. senile body wall in tidal currents is higher than that of A. xanthogrammica in wave surge, the moduli of walls from these species when exposed to such flow conditions are similar, between 0.1 and 0.3 MN.m−2.3. The flexural stiffness of M. senile is lowest in the upper column where the anemones bend in currents: this orients their filter-feeding oral discs normal to the currents. The flexural stiffness of A. xanthogrammica is one to two orders of magnitude higher than that of M. senile; A. xanthogrammica remain upright in wave surge and feed on mussels that fall on their oral discs.4. The deflexions of these anemones predicted using beam theory are consistent with those observed in nature.5. The critical stress to produce local buckling is an order of magnitude lower for M. senile than for A. xanthogrammica.6. Several general principles of the organization of cantilever-like sessile organisms are revealed by this study of sea anemones.

Cnidaria

1989 ◽  
Author(s):  
Heinz A. Lowenstam ◽  
Stephen Weiner
Keyword(s):  
Calcium Sulfate ◽  
Body Wall ◽  
Structural Features ◽  
The Body ◽  
Internal Space ◽  
Gravity Perception ◽  
Sessile Polyp ◽  
Gastrovascular Cavity ◽  
Mode Of Life ◽  
Pass Through

The phylum Cnidaria or Coelenterates includes sea anemones, jellyfish, hydras, sea fans, and, of course, the corals. With few exceptions they are all marine organisms and most are inhabitants of shallow water. In spite of the great variation in shape, size, and mode of life, they all possess the same basic metazoan structural features: an internal space for digestion (gastrovascular cavity or coelenteran), a mouth, and a circle of tentacles, which are really just an extension of the body wall. The body wall in turn is composed of three layers: an outer layer of epidermis, an inner layer of cells lining the gastrovascular cavity, and, sandwiched between them, a so-called mesoglea (Barnes 1980). All these features are present in both of the basic structural types: the sessile polyp and the free-swiming medusa. During their life cycle, some cnidarians exhibit one or the other structural type whereas others pass through both. Most Cnidaria have no mineralized deposits. The ones that, to date, are known to have mineralized deposits are listed in Table 5.1. They are found in both the free-swimming medusae and the sessile polyps. Not surprisingly, these have very different types of mineralized deposits. In the medusae they are located exclusively within the statocyst where they constitute an important part of the organism’s gravity perception apparatus. Interestingly the statoconia of the Hydrozoa, examined to date for their major elemental compositions only, are all composed of amorphous Mg-Ca-phosphate, whereas those of the Scyphozoa and Cubozoa are composed of calcium sulfate. Calcium sulfate minerals (presumably gypsum) are not commonly formed by organisms and the only other known occurrence is in the Gamophyta among the Protoctista. Spangenberg (1976) and her colleagues have expertly documented this phenomenon in the Cnidaria. (For a more detailed discussion of mineralization and gravity perception see Chapter 11.) The predominant mineralized hard part associated with the sessile polyps is skeletal. These can take the form of skeletons composed of individual spicules, spicule aggregates, or massive skeletons. They are composed of aragonite, calcite, or both.

scholarly journals Sperm Transfer Through the Vector Tissue in Piscicola Respirans (Clitellata, Hirudinea, Piscicolidae)

2009 ◽  
Vol 54-55 (1-4) ◽  
pp. 5-12 ◽  
Author(s):  
Piotr ŚwiĄtek ◽  
Anna Świder ◽  
Aleksander Bielecki
Keyword(s):  
High Pressure ◽  
Connective Tissue ◽  
Body Wall ◽  
The Body ◽  
Sperm Transfer ◽  
Ultrastructural Observation ◽  
Granular Cells ◽  
Main Mass ◽  
Tissue Cells ◽  
Cytoplasmic Processes

Sperm Transfer Through the Vector Tissue in Piscicola Respirans (Clitellata, Hirudinea, Piscicolidae) In fish leeches (Piscicolidae) indirect (hypodermic) insemination has evolved, thus the spermatophores are released in the specialised region of the body wall known as a copulatory area or a copulatory region. The way in which the spermatozoa reach the ovaries is not fully understood. In piscicolids beneath the copulatory area there is a specialized connective tissue (vector tissue), which is thought to guide the spermatozoa toward the ovaries. To date the structure of the vector tissue has not been observed in copulating specimens, which have spermatophores implanted in their coplulatory area. Here we present the first ultrastructural observation of massive sperm transfer from the spermatophore throughout the vector tissue to the ovaries. Our results show that the sperm transfer is both massive and rapid. The migrating spermatozoa form huge aggregations which push aside the vector tissue cells, in such a way that between these cells voluminous gaps are formed. Unexpectedly to our previous suggestions, the ultrastructural pictures show that the long cytoplasmic processes of granular cells, which constitute the main mass of the vector tissue, are not engaged in sperm transport. We suggest that the sperm is pumped with a high pressure from the spermatophore into the vector tissue, and as a result the vector tissue cells are pushed aside and spermatozoa can freely pass between them.

Surgical Anatomy of the Retroperitoneal Spaces–Part I: Embryogenesis and Anatomy

2009 ◽  
Vol 75 (11) ◽  
pp. 1091-1097 ◽  
Author(s):  
Petros Mirilas ◽  
John E. Skandalakis
Keyword(s):  
Connective Tissue ◽  
Abdominal Wall ◽  
Body Wall ◽  
Surgical Anatomy ◽  
The Body ◽  
Retroperitoneal Space ◽  
Variable Degree ◽  
Loose Connective Tissue ◽  
Posterior Abdominal Wall ◽  
Renal Fascia

Embryologically, the retroperitoneal (extraperitoneal) connective tissue includes three strata, which respectively form the internal fascia lining of the body wall, the renal fascia, and the covering of the gastrointestinal viscera. All organs, vessels, and nerves, that lie on the posterior abdominal wall, along with their tissues and surrounding connective and fascial planes, are collectively referred to as the retroperitoneum. The retroperitoneal space is the area of the posterior abdominal wall that is located between the parietal peritoneum and the fascia. Within the greater retroperitoneal space, there are also several small spaces, or subcompartments. Loose connective tissue and fat surround the anatomic entities, and, to a variable degree, occupy the subcompartments. The multilaminar thoracolumbar (lumbodorsal) fascia begins at the occipital area and terminates at the sacrum.

scholarly journals THE PLATING OF TUMOR COMPONENTS ON THE SUBCUTANEOUS EXPANSES OF YOUNG MICE

1962 ◽  
Vol 115 (6) ◽  
pp. 1211-1230 ◽  
Author(s):  
James S. Henderson ◽  
Peyton Rous
Keyword(s):  
Connective Tissue ◽  
Body Wall ◽  
Mammary Tumors ◽  
The Body ◽  
Subcutaneous Connective Tissue ◽  
Factor Type ◽  
Milk Factor ◽  
Forcible Injection ◽  
Young Mice

A procedure analogous to the plating of bacteria is described whereby some complex tumors have been taken apart and their components separately propagated. It was the outcome of finding that the forcible injection of Locke's solution followed by air can be used to split the subcutaneous connective tissue of sucklings and weanlings horizontally over the entire expanse of their backs or bellies, without inducing any complicating inflammation. Tumor fragments suspended in Locke's were widely scattered on the surfaces thus exposed. Most of them remained where they had lodged on the body wall, and rapidly becoming fixed in place, formed growths protected by the overlying cutaneous layer—which, throughout many weeks, remained unattached either to the wall or to them. The procedure is more searching in its disclosure of tumor constituents than those currently employed, and it has the advantage that it preserves the neoplastic components that it reveals. It has been used thus far only to rescue for experimental purposes transplantable, benign, epidermal papillomas from the hidden carcinomas deriving from their cells, and to set free and maintain the neoplastic components of complex mammary tumors of milk factor type. Success was obtained with such of the latter as were chosen for separate propagation, though successive platings were sometimes required for their isolation. Incidentally the procedure revealed two components in the mammary growths which could not have been discerned by previous methods of search. Each formed tumors peculiar to itself.

Effects of collagenase type I on the structural features of collagen fibres from sea cucumber (Stichopus japonicus) body wall

2019 ◽  
Vol 301 ◽  
pp. 125302 ◽  
Author(s):  
Yu-xin Liu ◽  
Zi-qiang Liu ◽  
Liang Song ◽  
Qian-ru Ma ◽  
Da-yong Zhou ◽  
...  
Keyword(s):  
Sea Cucumber ◽  
Body Wall ◽  
Structural Features ◽  
Type I ◽  
Collagen Fibres ◽  
Stichopus Japonicus

Observations on the anatomy of mammary glands in two species of conilurine rodent (Muridae: Hydromyinae) and in an opossum (Marsupialia: Didelphidae).

1993 ◽  
Vol 16 (1) ◽  
pp. 9
Author(s):  
M. Griffiths ◽  
N.G. Simms
Keyword(s):  
Connective Tissue ◽  
Body Wall ◽  
Striated Muscle ◽  
Mammary Glands ◽  
Monodelphis Domestica ◽  
The Body ◽  
Rodent Species ◽  
Voluntary Muscle ◽  
The Subject

The pups of Pseudomys nanus and P. australis are attached to their mothers' teats for extended periods of time, analogous to the situation encountered in pouchless marsupials. The structures in the mammary glands involved in facilitating prolonged attachment are different in the two rodent species and both kinds are different from those in marsupial glands including those of Monodelphis domestica, the subject of the present study. In P. nanus, the teats are anchored to postero-ventrally directed, tubular diverticula of the body wall. In P. australis there are no diverticula. However, support for the mammary glands and teats is afforded by the body wall, in the form of two well-developed fan-shaped muscles dorsal to the mammary glands in conjunction with a broad lamina of connective tissue, smooth and striated muscle situated between the skin of the belly and the mammary glands. In M. domestica, the teats are anchored to swathes of striated voluntary muscle, derived from the ilio-marsupialis muscles which pass ventrally through the secretory parenchyma to be inserted onto the bases of the teats. Since this musculature has not been observed in the mammary glands of any eutherians so far studied, nor in those of Monotremata, it is put that it is a character unique to the Marsupialia.

Neural control of muscle relaxation in echinoderms

2001 ◽  
Vol 204 (5) ◽  
pp. 875-885 ◽  
Author(s):  
M.R. Elphick ◽  
R. Melarange
Keyword(s):  
Smooth Muscle ◽  
Connective Tissue ◽  
Body Wall ◽  
Muscle Relaxation ◽  
The Body ◽  
Body Wall Muscle ◽  
Asterias Rubens ◽  
Cardiac Stomach ◽  
Stichopus Japonicus ◽  
Neuronal Signalling

Smooth muscle relaxation in vertebrates is regulated by a variety of neuronal signalling molecules, including neuropeptides and nitric oxide (NO). The physiology of muscle relaxation in echinoderms is of particular interest because these animals are evolutionarily more closely related to the vertebrates than to the majority of invertebrate phyla. However, whilst in vertebrates there is a clear structural and functional distinction between visceral smooth muscle and skeletal striated muscle, this does not apply to echinoderms, in which the majority of muscles, whether associated with the body wall skeleton and its appendages or with visceral organs, are made up of non-striated fibres. The mechanisms by which the nervous system controls muscle relaxation in echinoderms were, until recently, unknown. Using the cardiac stomach of the starfish Asterias rubens as a model, it has been established that the NO-cGMP signalling pathway mediates relaxation. NO also causes relaxation of sea urchin tube feet, and NO may therefore function as a ‘universal’ muscle relaxant in echinoderms. The first neuropeptides to be identified in echinoderms were two related peptides isolated from Asterias rubens known as SALMFamide-1 (S1) and SALMFamide-2 (S2). Both S1 and S2 cause relaxation of the starfish cardiac stomach, but with S2 being approximately ten times more potent than S1. SALMFamide neuropeptides have also been isolated from sea cucumbers, in which they cause relaxation of both gut and body wall muscle. Therefore, like NO, SALMFamides may also function as ‘universal’ muscle relaxants in echinoderms. The mechanisms by which SALMFamides cause relaxation of echinoderm muscle are not known, but several candidate signal transduction pathways are discussed here. The SALMFamides do not, however, appear to act by promoting release of NO, and muscle relaxation in echinoderms is therefore probably regulated by at least two neuronal signalling systems acting in parallel. Recently, other neuropeptides that influence muscle tone have been isolated from the sea cucumber Stichopus japonicus using body wall muscle as a bioassay, but at present SALMFamide peptides are the only ones that have been found to have a direct relaxing action on echinoderm muscle. One of the Stichopus japonicus peptides (holothurin 1), however, causes a reduction in the magnitude of electrically evoked muscle contraction in Stichopus japonicus and also causes ‘softening’ of the body wall dermis, a ‘mutable connective tissue’. It seems most likely that this effect of holothurin 1 on body wall dermis is mediated by constituent muscle cells, and the concept of ‘mutable connective tissue’ in echinoderms may therefore need to be re-evaluated to incorporate the involvement of muscle, as proposed recently for the spine ligament in sea urchins.

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