Muscle receptors in cephalopods

1965 ◽  
Vol 161 (984) ◽  
pp. 392-402 ◽  
Keyword(s):  
Nerve Cells ◽  
Octopus Vulgaris ◽  
Muscle Fibres ◽  
Sepia Officinalis ◽  
Muscle Receptors ◽  
Intramuscular Nerve ◽  
Nerve Cords

Multipolar nerve cells with the characteristics of muscle receptors have been shown in the arms of Octopus vulgaris . The dendrites of these cells branch out into the muscle fibres and their axons make their way to small, intramuscular ganglion centres (ganglion of the sucker and intramuscular nerve cords), in which they seem to end. Multipolar nerve cells with characteristics similar to those of the cells described in Octopus have also been shown in the lip of Sepia officinalis . Such evidence permits one to think that these structures are more frequent in the cephalopods than has been suspected hitherto and it confirms the presence of a system of proprioceptors.

The musculature and nervous system of the plerocercoid larva of Dibothriorhynchus grossum (Rud.)

Parasitology ◽  
1941 ◽  
Vol 33 (4) ◽  
pp. 373-389 ◽  
Author(s):  
Gwendolen Rees
Keyword(s):  
Nervous System ◽  
Muscle Mass ◽  
Nerve Cells ◽  
The Body ◽  
Lateral Nerve ◽  
Posterior Median ◽  
The Brain ◽  
Ventral Muscle ◽  
Nerve Cords ◽  
Extrinsic Muscles

1. The structure of the proboscides of the larva of Dibothriorhynchus grossum (Rud.) is described. Each proboscis is provided with four sets of extrinsic muscles, and there is an anterior dorso-ventral muscle mass connected to all four proboscides.2. The musculature of the body and scolex is described.3. The nervous system consists of a brain, two lateral nerve cords, two outer and inner anterior nerves on each side, twenty-five pairs of bothridial nerves to each bothridium, four longitudinal bothridial nerves connecting these latter before their entry into the bothridia, four proboscis nerves arising from the brain, and a series of lateral nerves supplying the lateral regions of the body.4. The so-called ganglia contain no nerve cells, these are present only in the posterior median commissure which is therefore the nerve centre.

Coxal Muscle Receptors in the Crab: The Receptor Potentials of S and T Fibres in Response to Ramp Stretches

1971 ◽  
Vol 55 (3) ◽  
pp. 813-832
Author(s):  
B. M. H. BUSH ◽  
ALAN ROBERTS
Keyword(s):  
Motor Nerve ◽  
Large Diameter ◽  
Muscle Fibres ◽  
Dynamic Component ◽  
Static Responses ◽  
Basal Joint ◽  
Muscle Receptors ◽  
Shore Crabs ◽  
Static Nature ◽  
Receptor Muscle

1. Intracellular and extracellular recordings from the two large-diameter S and T sensory fibres of the posterior thoracico-coxal muscle receptor in shore crabs confirm the graded, dynamic-static nature of the receptor potentials evoked by stretching the receptor muscle, and the lack of afferent impulses. 2. Slow ramp-function stretches evoke receptor potentials with characteristic shapes, which differ between the two fibres in several respects: (i) The dynamic component in the S fibre resembles an algebraic sum of length and velocity responses and a variable initial ‘acceleration’ (?) transient, while in the T fibre it commonly declines (‘adapts’) during stretching, especially at greater velocities and starting lengths. (ii) On release of stretch the S fibre usually exhibits a ‘negative velocity response’, but the T fibre repolarizes rapidly often with a slight hyperpolarization. (iii) The dynamic response of the T fibre is generally greater than that of the S fibre, and increases more steeply and approximately logarithmically with stretch velocity over a 10- to 50-fold range. (iv) The ‘static response’ or degree of depolarization increases fairly linearly with receptor length in the S fibre but very non-linearly in the T fibre. (v) The T fibre displays pronounced hysteresis in its dynamic and static responses at increasing and decreasing lengths, but the S fibre shows little hysteresis. (vi) The T fibre but not the S fibre commonly shows small rapid oscillations or ‘noise’ superimposed upon strongly depolarized ‘static’ potentials. (vii) The S and T responses may be affected reciprocally by some forms of receptor muscle contraction. 3. Graded receptor potentials evoked in the ‘D’ fibre by stretching the non-muscular depressor-receptor strand of the coxo-basal joint show little hysteresis. 4. Receptor muscle fibres respond to motor nerve stimulation or spontaneous motor impulses from the thoracic ganglion with slow, facilitating and summating excitatory junctional potentials. 5. The mechanisms underlying the differences between S and T responses, and their functional significance to the animal, are discussed, and comparisons are drawn with other muscle receptors.

Ultrafiltration in the Branchial Heart Appendage of Dibranchiate Cephalopods: A Comparative Ultrastructural and Physiological Study

1981 ◽  
Vol 92 (1) ◽  
pp. 23-35
Author(s):  
R. SCHIPP ◽  
F. HEVERT
Keyword(s):  
Basal Lamina ◽  
Peripheral Blood ◽  
Sea Water ◽  
Physiological Study ◽  
Coelomic Fluid ◽  
Octopus Vulgaris ◽  
Sepia Officinalis ◽  
Branchial Heart ◽  
Urine Formation

It is shown that ultrafiltration could be the first step in urine formation in Sepia officinalis and Octopus vulgaris. The organization of the podocytes indicates that ultrafiltration can occur through these cells. They have a thick basal lamina in contact with the peripheral blood lacunae, and the cell apices lie in infoldings of the lumen of the appendage. Comparison between the colloid-osmotic and the hydrostatic pressures of the fluids in the branchial heart and the pericardial coelom shows that an ultrafiltration can take place during the branchial heart systole as well as during a long phase of the diastole. Comparison of the osmolalities of blood, coelomic fluid, renal-sac fluid, and sea water shows that these species are hypoosmotic regulators.

The Early Development of Muscle Spindles in the Rat

1973 ◽  
Vol 12 (1) ◽  
pp. 175-195
Author(s):  
ALICE MILBURN
Keyword(s):  
Close Association ◽  
Large Diameter ◽  
Muscle Spindles ◽  
Muscle Fibres ◽  
Intrafusal Muscle ◽  
Intrafusal Fibres ◽  
Fusimotor Innervation ◽  
Nuclear Chain ◽  
Intramuscular Nerve

The morphogenesis of muscle spindles in rat lower hind-limb muscles has been investigated using the electron microscope. The earliest detectable spindles are seen in the 19.5-day foetus and consist of a single myotube bearing simple nerve terminals of the large primary afferent axon from nearby unmyelinated intramuscular nerve trunks. The capsule forms by an extension of the perineural epithelium of the supplying nerve fasciculus, and is confined initially to the innervated zone. Myonuclei accumulate in this region, so that the first intrafusal muscle fibre to develop is a nuclear-bag fibre. Myoblasts, present within the capsule of the spindle throughout its development, fuse to form a smaller less-differentiated myotube by the 20-day foetal stage. This new myotube matures by close association with the initial fibre, and by birth (21-22 days gestation) has formed the smaller, intermediate bag fibre, that has been identified histochemically and ultrastructurally in the adult. The nuclear-chain fibres develop in the same way; myoblasts fuse to form satellite myotubes that mature in pseudopodial apposition to one of the other fibres within its basement membrane. This apposition consists of extensions of sarcoplasm from the developing myotube into the supporting fibre. By the 4-day postnatal stage the full adult complement of 4 intrafusal muscle fibres is present, although ultrastructural variations, seen in the adult, are not differentiated. The fusimotor innervation begins to arrive at birth, but is not mature until the 12th postnatal day, when the myofibrillar ultrastructural differentiation, including the loss of the M-line in the large-diameter bag fibre, is complete. The periaxial space appears at the same time. It is suggested that the sequential development of the intrafusal fibres is a reflexion of the decreasing morphogenetic effect of the afferent innervation, whereas the role of the fusimotor innervation is in ultrastructural, myofibrillar differentiation.

Sterols of the Cephalopod Spirula Spirula

1981 ◽  
Vol 61 (4) ◽  
pp. 843-850 ◽  
Author(s):  
James A. Ballantine ◽  
John C. Roberts ◽  
Robert J. Morris
Keyword(s):  
Sterol Composition ◽  
The Other ◽  
Octopus Vulgaris ◽  
Detailed Knowledge ◽  
Sepia Officinalis ◽  
Dietary Components ◽  
Dietary Origin

The sterol biochemistry of the highly advanced molluscan class – the cephalopods – is poorly understood. Few analyses of their component sterols have been published in which GC-MS has been employed (Voogt, 1973; Idler et al. 1978; ApSimon & Burnell, 1980) and these have only involved 5 species.From the available data the cephalopods appear to have a much simpler sterol make-up than the other less-advanced molluscs. Cholesterol appears to be easily the predominant sterol (ca. 90%) with minor amounts of up to 10 other common marine sterols. Of the species analysed, four (Sepia officinalis, Octopus vulgaris, Eledone aldrovandi and Illex illecebrosus) had a very similar major and minor sterol composition. Only the more primitive Nautilus sp. (Idler et al. 1978) had a noticeably different minor sterol composition.Voogt (1973) reported cephalopods to be able to synthesise sterols though molluscs generally appear only to be able to carry out this biosynthesis slowly (Goad, 1978). Cephalopods are extremely active carnivores and thus would be expected to have a diverse diet. If their component sterols are of a dietary origin, a considerable variation in their minor sterol composition might be expected on the basis of the range in sterol composition reported for pelagic organisms (e.g. Morris & Culkin, 1977), many of which may be possible dietary components.Detailed knowledge however of cephalopod diets is limited. Quite apart from the fact that healthy specimens are rarely caught in nets, those that are caught often feed voraciously on the other organisms trapped in the net prior to being brought on board for examination.

The Nerve-net of Metridium senile: Artifacts and the Nerve-net

1961 ◽  
Vol s3-102 (58) ◽  
pp. 143-156
Author(s):  
E. J. BATHAM ◽  
C.F. A. PANTIN ◽  
E. A. ROBSON
Keyword(s):  
Nervous System ◽  
Nerve Cells ◽  
Muscle Fibres ◽  
Nerve Net ◽  
Metridium Senile ◽  
Staining Methods ◽  
Epithelial Layers

The present paper follows an account of the structure of the nervous system of Metridium senile(L.). Conflicting statements about the actinian nervous system in the earlier literature made it necessary to assess the results of previous workers critically. Several of their methods have now been repeated and compared with our results after using more specific techniques. The criteria for distinguishing nerve-cells from nonnervous elements in actinians are discussed. Mesogloeal fibres, amoebocytes, nematocyst threads, and muscle-fibres may on occasion be confused with nerve-cells, and deteriorating nerve-cells may also have a misleading appearance. Gross artifacts may be reduced by the use of special staining methods, and on the basis of this work the results of several earlier authors have been re-interpreted. It is concluded that the nervous system in the mesenteries and column of Metridium follows the epithelial layers and does not penetrate the mesogloea.

Studies of Cardio-Regulation in the Cockroach, Periplaneta Americana

1971 ◽  
Vol 54 (2) ◽  
pp. 329-350
Author(s):  
T. MILLER ◽  
P. N. R. USHERWOOD
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Heart Muscle ◽  
Periplaneta Americana ◽  
Ganglion Cells ◽  
Muscle Fibres ◽  
Cardiac Ganglion ◽  
Cardiac Nerve ◽  
The Central Nervous System ◽  
Nerve Cords

1. The heart of Periplaneta americana is segmentally innervated from the central nervous system by three types of neurone. Two of these types of neurones are neurosecretory; one type contains large granules, the other small granules. The segmental nerves are paired structures which join paired lateral cardiac nerve cords. Both types of neurosecretory neurone liberate their contents in the lateral cardiac nerve cords. The neurones with the small granules also synapse with the myocardium as well as with intrinsic cardiac neurones in the lateral cardiac nerve cords. The third type of neurone from the central nervous system is an ordinary efferent neurone and it synapses with the cardiac ganglion cells. 2. A heart chamber is associated with about six cardiac ganglion cells, three on either side. These send processes up and down the lateral cardiac nerve cord and make synaptic contact with the myocardium. 3. The myocardium is multiterminally and polyneuronally innervated, and electrical coupling between muscle fibres appears to be the rule. The fibres are spontaneously active and generate spike-like electrically excited responses. The timing of the electrically excited responses is influenced by the input from the cardiac ganglion cells which evoke a burst of synaptic potentials during diastole. 4. Control of the cockroach heart appears to be organized on three levels. The basic rhythm is myogenic. The timing of the contractions is influenced by inputs from the intrinsic cardiac ganglion cells possibly via a feedback mechanism involving the contractions of the heart muscle. Finally, the activities of the heart muscle and the cardiac ganglion cells are influenced by inputs from the central nervous system.

Contractile properties of obliquely striated muscle from the mantle of squid (Alloteuthis subulata) and cuttlefish (Sepia officinalis)

1997 ◽  
Vol 200 (18) ◽  
pp. 2425-2436 ◽  
Author(s):  
B Milligan ◽  
N Curtin ◽  
Q Bone
Keyword(s):  
Striated Muscle ◽  
Maximum Power ◽  
Muscle Fibres ◽  
Sepia Officinalis ◽  
Cross Sectional ◽  
Tetanic Force ◽  
Velocity Relationship ◽  
Locomotor Muscles ◽  
Isometric Twitch ◽  
Force Relationship

The mechanical properties of obliquely striated muscle fibres were investigated using thin slices of mantle from squid Alloteuthis subulata and cuttlefish Sepia officinalis. Brief tetani or twitch stimuli were used as this pattern is likely to occur during jetting of the intact animal. The length­active force relationship for twitches and tetani (0.1s, 50Hz) was similar to that of vertebrate cross-striated fibres. Passive force at the length giving maximum tetanic force was 0.13±0.05P0 (mean ± s.e.m., N=6, where P0 is maximum isometric tetanus force) and increased steeply at longer lengths. Peak force in a brief isometric tetanus (0.2s, 100­150Hz) was 262±16mNmm-2 cross-sectional area of wet tissue (N=6) for squid, and 226±19mNmm-2 (N=7) for cuttlefish. The force­velocity relationship for isotonic shortening during twitches of squid mantle slices was a 'double hyperbolic' relationship as described for cross-striated fibres by Edman. Fitting Edman's equation to the results gave: P*=1.18±0.07, Vmax=2.43±0.11Ltws-1 and 1/G=0.69±0.13 (N=8), where P* is the intercept on the force axis expressed relative to Ptw, peak isometric twitch force, Vmax is the intercept on the velocity axis, Ltw is the length at which Ptw is produced and G is the constant expressing curvature. The large values of 1/G indicate that the force­velocity relationship is not very curved. Maximum power was produced during shortening at 0.45±0.03Ptw (N=8). Maximum power during twitch contraction was 18.3±1.7mWg-1wetmass or, expressed in relative units, (V/Vmax)(P/Ptw), where V is the velocity during shortening and P is the force during shortening, was 0.16±0.01 (N=8), which is higher than that of many cross-striated locomotor muscles.

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