scholarly journals THE STRUCTURE OF THE SMOOTH MUSCLE FIBRES IN THE BODY WALL OF THE EARTHWORM

1957 ◽  
Vol 3 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Jean Hanson
Keyword(s):  
Smooth Muscle ◽  
Phase Contrast ◽  
Body Wall ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Mirror Image ◽  
The Body ◽  
The Other ◽  
Muscle Fibres ◽  
Muscle Coat

1. The structure of the smooth muscle fibres in the longitudinal muscle coat of the body wall of Lumbricus terrestris has been investigated by phase contrast light microscopy and electron microscopy. 2. The muscle fibre is ribbon-shaped, and attached to each of its two surfaces is a set of myofibrils. These are also ribbon-shaped, and they lie with their surfaces perpendicular to the surfaces of the fibre, and their inner edges nearly meeting in the middle of the fibre. These fibrils are oriented at an angle to the fibre axis, and diminish greatly in width as they approach the edge of the fibre. The orientation of the set of fibrils belonging to one surface of the fibre is the mirror image of that of the set belonging to the other surface; thus, when both sets are in view in a fibre lying flat on one face, the fibre exhibits double oblique striation. A comparison of extended and contracted fibres indicates that as the fibre contracts, the angle made between fibre and fibril axes increases (e.g. from 5 to 30°) and so does the angle made between the two sets of fibrils (e.g. from 10 to 60°). 3. The myofibril, throughout its length, contains irregularly packed filaments, commonly 250 A in diameter, which are parallel to its long axis and remain straight in contracted muscles. Between them is material which probably consists of much finer filaments. Thus A and I bands are absent. 4. Bound to one face of each fibril, but not penetrating inside it, is a regularly spaced series of transverse stripes. They are of two kinds, alternating along the length of the fibril, and it is suggested that they are comparable to the Z and M lines of a cross-striated fibril. The spacing of these stripes is about 0.5 µ ("Z" to "Z") in extended muscles, and 0.25 µ in contracted muscles. A bridge extends from each stripe across to the stripeless surface of the next fibril.

Memoirs: On the Reproductive Processes of the Earthworm, Lumbricus Terrestris

1925 ◽  
Vol s2-69 (274) ◽  
pp. 245-290
Author(s):  
A. J. GROVE
Keyword(s):  
Body Wall ◽  
Seminal Fluid ◽  
Lumbricus Terrestris ◽  
The Body ◽  
The Other ◽  
Reproductive Processes ◽  
Longitudinal Muscles ◽  
Earthworm Lumbricus

During the sexual congress of L.terrestris, the co-operating worms become attached to one another in a head-to-tail position in such a way that segments 9-11 of one are opposed to the clitellum of the other, and vice versa. At these points the attachment between the worms is an intimate one, assisted by the secretion of the glands associated with the diverticula of the setal pores found in certain segments, and is reinforced by the mutual penetration of the setae into the opposed body-surfaces. There is also a slighter attachment between segment 26 of one and 15 of the other. Each worm is enclosed in a slime-tube composed of mucus secreted from the epidermis. The exchange of seminal fluid is a mutual one. The fluid issues from the apertures of the vasa deferentia in segment 15, and is conducted beneath the slime-tube in pit-like depressions in the seminal grooves, which extend from segment 15 to the clitellum on each side of the body, to the clitellum, where it accumulates in the space between the lateral surfaces of segments 9-11 of one worm and the clitellum of the other. Eventually it becomes aggregated into masses in the groove between segments 9 and 10, and 10 and 11, and passes thence into the spermathecae. The seminal groove and its pit-like depressions are brought into existence by special muscles lying in the lateral blocks of longitudinal muscles of the body-wall.

Neuromuscular Junctions in the Body Wall Muscles of the Earthworm, Lumbricus Terrestris Linn

1970 ◽  
Vol 7 (1) ◽  
pp. 263-271
Author(s):  
P. J. MILL ◽  
M. F. KNAPP
Keyword(s):  
Synaptic Vesicles ◽  
Body Wall ◽  
Neuromuscular Junctions ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Dense Material ◽  
Muscle Fibres ◽  
Membrane Material ◽  
Axonal Membrane ◽  
Body Wall Muscles

The fine structure of the neuromuscular Junctions in the body wall muscles of the earthworm is described. The segmental nerves send branches into the muscle layers. Axons in the nerve branches contain numerous synaptic vesicles and contact is established between these axons and muscle fibres or muscle tails; the latter may extend for a considerable distance from the muscle fibre. The cleft between the axolemma and sarcolemma is 85-120 nm wide and contains basement membrane material. At intervals small aggregations of electron-dense material are attached to the axonal membrane and synaptic vesicles are associated with these. The sarcolemma bears rather larger masses of dense material and is also specialized extracellularly.

scholarly journals The Contractile Mechanism in Obliquely Striated Body Wall Muscle of the Earthworm, Lumbricus Terrestris

1971 ◽  
Vol 8 (2) ◽  
pp. 413-425 ◽  
Author(s):  
M. F. KNAPP ◽  
P. J. MILL
Keyword(s):  
Body Wall ◽  
Striated Muscle ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Band Width ◽  
Physiological Data ◽  
Muscle Fibres ◽  
Contraction Mechanism ◽  
Cross Links

Obliquely striated muscle fibres from the longitudinal and circular layers of the body wall of the earthworm were prepared in extended and contracted states for study in the electron microscope. Contracted fibres differ from extended ones in the following respects: (i) the I-bands are narrower, (ii) the A-bands are wider, and (iii) there are more rows of thick myofilaments in each A-band. The arrangement of the thick and thin myofilaments in interdigitating arrays and the occurrence of cross-links between the 2 types of myofilament indicate a classical sliding-filament mechanism of contraction as in cross-striated muscle, resulting in a reduction in the I-band width. The increase in the A-band width could be due to a moving apart of the myofilaments during contraction to preserve constant volume of the lattice. The third change, the increase in the number of rows of thick myofilaments in the A-band, can be explained only by a shearing of these filaments past one another in such a way as to increase the amount of their overlap. The role of the sliding-filament and shearing contraction mechanisms in bringing about the changes observed in earthworm muscle fibres is considered and the possible correlation of these mechanisms with certain physiological data is discussed. The function of the sarcoplasmic reticulum in the transmission of impulses to the interior of the fibre and/or in the control of the contraction mechanism is also discussed.

The Fine Structure of Obliquely Striated Body Wall Muscles in the Earthworm, Lumbricus Terrestris LINN

1970 ◽  
Vol 7 (1) ◽  
pp. 233-261
Author(s):  
P. J. MILL ◽  
M. F. KNAPP
Keyword(s):  
Fine Structure ◽  
Body Wall ◽  
Striated Muscle ◽  
Thin Sheet ◽  
Lumbricus Terrestris ◽  
Acute Angle ◽  
The Body ◽  
Fibre Axis ◽  
Muscle Fibres ◽  
Longitudinal Fibre

The fine structure of obliquely striated muscle fibres from the body wall of the earthworm has been investigated. Certain details of the structure have been confirmed by cutting serial sections. The fibres contain both thick and thin myofilaments. The latter are attached to Z-material and the 2 types of myofilament are arranged in interdigitating arrays to give rise to A- and I-bands and an H-zone similar to those in cross-striated muscle. The A-bands contain both thick and thin myofilaments and the I-bands only thin myofilaments. The Z-material is rod-shaped and these Z-rods, oriented perpendicular to the sarcolemma, are arranged in numerous parallel rows which run obliquely along the length of the fibre A line drawn parallel to the longitudinal fibre axis through a Z-rod in one row passes through a Z-rod in the next row. A thin, sheet-like array of myofilaments lies between 2 such Z-rods, forming a single sarcomere containing an A-band and 2 I-bands. The flat surfaces of neighbouring sarcomeres are directly apposed to one another but, since the rows of Z-rods run diagonally along the length of the fibre, each sarcomere is displaced longitudinally with respect to the next, so that the A- and I-bands follow an oblique course, instead of a transverse course as in cross-striated muscle. Because of the regular stagger of the sarcomeres A- and I-bands are cut alternately in transverse sections. Also the sarcomeres are very narrow and are seen as bands lying perpendicular to the sarcolemma. In the A-band a variable number of thin myofilaments (up to 12) surrounds each thick one. Cross-links have been seen between the 2 types of filaments. In longitudinal sections an appearance similar to that seen in cross-striated muscle is obtained in one plane (perpendicular to the sarcolemma). In the plane at right angles to this (parallel to the sarcolemma) the A- and I-bands are at an acute angle to the longitudinal fibre axis. The thick myofilaments exhibit a banding of about 15 nm. There is a system of transversely oriented tubules and peripheral vesicles with dyad-like structures occurring at the juxtaposition between the penpheral vesicles and the sarcolemma. It is concluded that this system is sarcoplasmic reticulam, and it is compared with tubular systems in other muscles. Other cellular constituents are described, including a peripheral skeleton of fibrillar bundles.

Head waving in Aplysia californica. II. Functional anatomy and muscular activity during behaviour.

1994 ◽  
Vol 195 (1) ◽  
pp. 53-74
Author(s):  
F M Kuenzi ◽  
T J Carew
Keyword(s):  
Muscle Activity ◽  
Body Wall ◽  
Longitudinal Muscle ◽  
Aplysia Californica ◽  
The Body ◽  
Vertical Posture ◽  
Muscle Fibres ◽  
Spatial And Temporal Patterns ◽  
Head Region ◽  
Muscle Fascicles

Bending and twisting movements of the body during head-waving behaviour of the sea hare Aplysia californica are produced by the concerted action of the muscles of the body wall on the hydrostatic skeleton formed by the haemocoel and internal organs. In this study, we describe the orientations and possible mechanical actions of muscles in the body wall. We also describe the spatial and temporal patterns of longitudinal muscle activity during different head-waving movements in a freely moving animal. The body-wall muscles are arranged as a network of longitudinal, circular and left- and right-handed helical muscle fascicles. Each fascicle consists of a few to several hundred muscle fibres enclosed in a connective tissue sheath. The sheath also connects muscle fascicles of different orientations at the points where they cross, forming a tightly connected network. In addition, a series of large longitudinal muscle fascicles, including the lateral columellar muscles, lies against the inside wall of the dorsal hemicylinder of the animal. In animals with hydrostatic skeletons, longitudinal and circular muscles are necessary for producing all basic elongation, shortening and bending movements, and in Aplysia, the extensive distribution of helical muscles provides the animal with the ability to twist its body about the longitudinal axis, as is observed during horizontal head-waving movements. Muscle activity in the lateral muscles is antiphasically coordinated during horizontal bends, and when the animal is bent to one side, movement towards the centre is accompanied by muscle activity on the side of shortening, i.e. there is no passive return to centre. The muscles near the holdfast are the most active during head-waving movements, with relatively little activity in the head region. The activity of dorsal muscles corresponds to both the existing vertical posture of the body and to discrete dorsal bending movements. In most cases, depression of the head is passive, i.e. both dorsal and ventral longitudinal muscles relax, although foot muscles may also be involved. These observations, together with the constancy of the hydrostatic pressure in the haemocoel during all movements in animals attached to the substratum, suggest specific patterns of motor neurone coordination during different movements.

Mediolateral somitic origin of ribs and dermis determined by quail-chick chimeras

Development ◽  
2000 ◽  
Vol 127 (21) ◽  
pp. 4611-4617 ◽  
Author(s):  
I. Olivera-Martinez ◽  
M. Coltey ◽  
D. Dhouailly ◽  
O. Pourquie
Keyword(s):  
Skeletal Muscles ◽  
Body Wall ◽  
Primitive Streak ◽  
Axial Skeleton ◽  
Lateral Compartment ◽  
The Body ◽  
The Other ◽  
Lateral Part ◽  
Respective Contribution ◽  
Epaxial Muscles

Somites are transient mesodermal structures giving rise to all skeletal muscles of the body, the axial skeleton and the dermis of the back. Somites arise from successive segmentation of the presomitic mesoderm (PSM). They appear first as epithelial spheres that rapidly differentiate into a ventral mesenchyme, the sclerotome, and a dorsal epithelial dermomyotome. The sclerotome gives rise to vertebrae and ribs while the dermomyotome is the source of all skeletal muscles and the dorsal dermis. Quail-chick fate mapping and diI-labeling experiments have demonstrated that the epithelial somite can be further subdivided into a medial and a lateral moiety. These two subdomains are derived from different regions of the primitive streak and give rise to different sets of muscles. The lateral somitic cells migrate to form the musculature of the limbs and body wall, known as the hypaxial muscles, while the medial somite gives rise to the vertebrae and the associated epaxial muscles. The respective contribution of the medial and lateral somitic compartments to the other somitic derivatives, namely the dermis and the ribs has not been addressed and therefore remains unknown. We have created quail-chick chimeras of either the medial or lateral part of the PSM to examine the origin of the dorsal dermis and the ribs. We demonstrate that the whole dorsal dermis and the proximal ribs exclusively originates from the medial somitic compartment, whereas the distal ribs derive from the lateral compartment.

A new genus and species of Sclerodactylidae (Echinodermata: Holothuroidea: Sclerothyoninae) from the Pacific coast of Panama, and assignment of Neopentamera anexigua to Sclerothyoninae

Zootaxa ◽  
2018 ◽  
Vol 4429 (1) ◽  
pp. 157
Author(s):  
LUCIANA MARTINS ◽  
MARCOS TAVARES
Keyword(s):  
Body Wall ◽  
New Genus ◽  
Pacific Coast ◽  
The Body ◽  
The Other ◽  
Monotypic Genus ◽  
New Genus And Species ◽  
The Pacific ◽  
Calcareous Ring

Paulayellus gustavi, a new sclerodactylid genus and species, is described from the Pacific coast of Panama. The new genus and species is assigned to the subfamily Sclerothyoninae based on a suite of characters, which include the radial and interradial plates of the calcareous ring united at the base only. Paulayellus gen. nov. differs from the other Sclerothyoninae genera in having posterior processesof radial plates undivided. Additionally, differs from Sclerothyone, Thandarum and Neopentamera in having knobbed buttons, plates and cups in the body wall (whereas the body wall is furnished only with tables and plates in Sclerothyone, Temparena and Thandarum, and only with knobbed buttons and plates in Neopentamera). The new genus is, so far, monotypic. The also monotypic genus Neopentamera proved to have the radial and the interradial plates of the calcareous ring united at the base only, as typically found in the Sclerothyoninae, and is therefore transferred to that subfamily. The discovery of a new genus in the Sclerothyoninae and the transfer of Neopentamera required the amendation of the diagnosis for the subfamily. A key to the Sclerothyoninae is given. 

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 453-467
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Time Course ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Single Pulse ◽  
Repetitive Stimulation ◽  
Muscle Fibres ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus ◽  
Stimulation Of

1. Patterns of innervation of the longitudinal muscle of the earthworm, Lumbricus terrestris, were examined electrophysiologically. 2. The longitudinal musculature of a segment is innervated by relatively few axons, a fast and slow axon being present in segmental nerve I and in the double nerve, segmental nerve II-III. 3. Single-pulse stimulation of the fast axon produces large external muscle potentials and small twitch-like contractions, which with repetitive stimulation are antifacilitating. 4. Repetitive stimulation of the slow axon produces large, slowly developing and sustained mechanical responses, with electrical and mechanical responses showing summation and facilitation. 5. The amplitude and time course of slow mechanical responses are related to the frequency of stimulation. 6. Individual longitudinal muscle fibres are innervated by either the fast or slow axon in a segmental nerve, or by both fast and slow axons. 7. No evidence was found for peripheral inhibitory innervation of the longitudinal muscle.

The Cuticle of Peripatopsis Moseleyi

1964 ◽  
Vol s3-105 (71) ◽  
pp. 281-299
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Body Wall ◽  
Light And Electron Microscopy ◽  
Thick Layer ◽  
The Body ◽  
Muscle Fibres ◽  
Terrestrial Arthropods ◽  
Dermal Glands ◽  
Arthropod Cuticle ◽  
Primitive Condition ◽  
Pore Canals

The integument of Peripatopsis moseleyi has been examined by light and electron microscopy with particular reference to the structure and formation of the cuticle. The evidence supports the idea that Peripatus is a true arthropod but not that it has direct affinities with the annelids. The characteristics of arthropod cuticle are present in their simplest form and pore canals and dermal glands are lacking. The cuticle is 1 or 2 µ, thick except in the hardened claws and spines. Above the procuticle (chitinprotein) is a thin 4-layered epicuticle. It is possible that the innermost of the 4 layers (prosclerotin) may correspond to cuticulin of other arthropods. In the claws and spines tanning in this layer extends to the procuticle. Hydrofuge properties of the cuticle probably depend on the outer layers of epicuticle, and it is suggested that the lamina concerned might consist of oriented lipid associated with lipoprotein (Dr. J. W. L. Beament). Wax and cement are absent. Non-wettability of the cuticle is probably ensured by the contours of micropapillae which cover the surface. Similar structures arise in Collembola and other terrestrial arthropods by convergence. The formation of new cuticle before ecdysis is described. After the epicuticular layers are complete, the bulk of the procuticle is laid down in a manner probably common to all arthropods. Secreted materials originate in small vesicles derived from rough endoplasmic reticulum and from scattered Golgi regions. The latter contribute to larger vacuoles which rise to the surface of the cell and liberate material in a fluid state. This later consolidates to form procuticle. Vesicles may also open to the surface directly, and ribosomes probably occur free in the cytoplasm. At this stage the cell surface is reticulate, especially under micropapillae. The ordinary epidermis has only one kind of cell, attached to the cuticle by tonofibrils disposed like the ribs of a shuttlecock, and to the fibrous sheaths of underlying muscle-fibres by special fibres of connective tissue. These features and the presence of numerous sensory papillae are associated with the characteristic mobility of the body wall. The appearance of epidermal pigment granules, mitochondria, the nuclear membrane, and a centriole are noted. No other cells immediately concerned in the formation of cuticle have been found. By contrast myriapods, which do not have wax either, possess dermal glands secreting far more lipid than is found in the Onychophora. The wax layer found in insects and some arachnids constitutes an advance of high selective value which emphasizes the primitive condition of the Onychophora. It is noted that the thick layer of collagen separating the haemocoel from the epidermis probably restricts the transfer of materials. It is suggested that since some features of cuticular structure and formation appear to be common to all arthropods, it is possible that some of the endocrine mechanisms associated with ecdysis may also be similar throughout the phylum.

Isolated Giant Smooth Muscle Fibres in Beroe Ovata: Ionic Dependence of Action Potentials Reveals Two Distinct Types of Fibre

1988 ◽  
Vol 135 (1) ◽  
pp. 343-362 ◽  
Author(s):  
ANDRÉ BILBAUT ◽  
ROBERT W. MEECH ◽  
MARI-LUZ HERNANDEZ-NICAISE
Keyword(s):  
Smooth Muscle ◽  
Action Potential ◽  
Action Potentials ◽  
Marine Invertebrate ◽  
The Body ◽  
Fibre Types ◽  
Resting Membrane Potential ◽  
Muscle Fibres ◽  
Beroe Ovata ◽  
Radial Muscle

1. The ionic dependence of action potentials evoked in giant smooth muscle fibres isolated by enzymatic digestion from the body wall of the marine invertebrate Beroe ovata (Ctenophora) has been investigated using conventional electrophysiological techniques. 2. Differences were observed in the two fibre types studied. The resting membrane potential was −60 ± 1.35 mV (N = 25) in longitudinal muscle fibres and −66 ±1.37 mV (N=32) in radial fibres. Action potentials had a short plateau in longitudinal fibres but not in radial fibres. 3. The action potential overshoot of both fibre types was decreased in Ca2+-free artificial sea water (ASW). In Na+-deficient ASW, action potentials could not be generated in radial fibres and showed a reduced overshoot in longitudinal fibres. 4. Tetrodotoxin (10−5moll−5) added to ASW or Ca2+-free ASW did not affect the action potentials of either type of fibre. 5. Action potentials of both fibres were partially blocked by Co2+ (20–50 mmoll−1) or Cd2+ (l-2mmoll−1). Action potentials of longitudinal fibres in Na+-deficient ASW were abolished by Co2+ (20mmoll−1). In Ca2+-free ASW, the ction potential overshoots of both sets of fibres were restored following the addition of Sr2+ or Ba2+. In longitudinal fibres, Sr2+ increased the duration of the action potential plateau. In both longitudinal and radial muscle fibres, Ba2+ prolonged the action potential. 6. In longitudinal fibres exposed to tetraethylammonium chloride (TEAC1) or 4-aminopyridine (4AP), the action potential was slightly prolonged. In these fibres, TEA+ or 4AP added to Ca2+-free ASW induced only a long-lasting depolarizing plateau. In radial fibres, the action potential duration was slightly increased in the presence of TEA+; it was unaffected by 4AP. In Ca2+-free ASW, TEA+ and 4AP induced an oscillating membrane response which appeared to be dependent on the intensity of the injected current pulse. 7. It is concluded that (a) there are significant differences between the action potentials of longitudinal and radial muscle fibres but that both are dependent on Na+ and Ca2+, (b) in longitudinal fibres, a Ca2+-activated K+ conductance and a TEA+-sensitive voltage-activated K+ conductance contribute to the repolarizing phase of the action potential, the former being predominant, (c) in radial fibres, the repolarizing phase of action potentials probably involves different membrane K+ conductances among which is a TEA+-sensitive K+ conductance.

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