Cholinergic Motor Control of Sea Urchin Tube Feet: Evidence for Chemical Transmission without Synapses

1980 ◽  
Vol 88 (1) ◽  
pp. 281-292
Author(s):  
E. FLOREY ◽  
M. A. CAHILL
Keyword(s):  
Electrical Stimulation ◽  
Connective Tissue ◽  
Outer Surface ◽  
Muscle Fibres ◽  
Nerve Terminals ◽  
Tissue Layer ◽  
Connective Tissue Layer ◽  
Electrical Stimuli ◽  
Tube Feet ◽  
Chemical Transmission

Isolated tube feet of Strongylocentrotus franciscanus contract briefly when the outer epithelium is touched. Similar twitch-like contractions can be induced by electrical stimulation of the outer surface of the tube foot. These responses appear to be chemically mediated. The following evidence indicates that the transmitter substance may be acetylcholine (ACh): ACh causes muscle contraction. This effect and that of electrical stimuli is potentiated by anticholinesterase agents and is antagonized by cholinergic blocking agents. Anaesthesia with chloralhydrate or chloretone abolishes responsiveness to mechanical or electrical stimulation but not to ACh. Desensitization with carbachol prevents responses to ACh and to mechanical or electrical stimulation. There are no neuromuscular synapses and no axons can be detected which cross the connective tissue layer which separates the muscle fibres from the subepithelial nerve plexus. The latter is known to contain conspicuous amounts of ACh; nerve terminals containing clear vesicles invest the outer surface of the connective tissue layer. All evidence indicates that chemical transmission involves diffusion of ACh (released from activated nerve terminals) across this connective tissue layer which is around 5 μm thick in fully extended tube feet but may have a thickness of 20 or even 25 μm in less extended ones. Calculations based on equations describing transmitter diffusion prove the feasibility of such a mechanism. Note:

scholarly journals Effects of age on growth and development of vagina in ISA Brown chickens

2012 ◽  
Vol 28 (2) ◽  
pp. 75-79
Author(s):  
K. A. Ferdous ◽  
M. N. H. Parvez ◽  
M. T. Rahman
Keyword(s):  
Smooth Muscle ◽  
Connective Tissue ◽  
Growth And Development ◽  
Structural Changes ◽  
Columnar Epithelium ◽  
Muscle Fibres ◽  
Adult Bird ◽  
Tissue Layer ◽  
Connective Tissue Layer ◽  
Mucosal Folds

Structure and postnatal development of vagina in 21 ISA brown chickens was studied at three, 23 and 46 weeks of age. At 3 weeks of age the vagina was narrower and thicker then the uterus. The undifferentiated wall of vagina consisted of low primary mucosal folds lined by simple columnar epithelium to a pseudostratified ciliated columnar epithelium and a connective tissue layer underneath. At three weeks of age, scattered smooth muscle fibres were in the subepithelial connective tissue layer. Rapid structural changes occurred at 23 weeks of age in the adult bird, mucosal folds were narrowed and tongue-shaped. Lamina propia was devoid of glands and contained lymphocytes. Tunica muscularis was well developed at 23 and 46 weeks.DOI: http://dx.doi.org/10.3329/bvet.v28i2.10676Bangl. vet. 2011. Vol. 28, No. 2, 75 – 79

Alteration of the brood pouch morphology during gestation of male seahorses, Hippocampus kuda

2006 ◽  
Vol 57 (5) ◽  
pp. 497 ◽  
Author(s):  
Parichart Laksanawimol ◽  
Praneet Damrongphol ◽  
Maleeya Kruatrachue
Keyword(s):  
Smooth Muscle ◽  
Connective Tissue ◽  
Blood Vessels ◽  
Muscle Layer ◽  
Brood Pouch ◽  
Muscle Fibres ◽  
Tissue Layer ◽  
Loose Connective Tissue ◽  
Connective Tissue Layer ◽  
Normal Stage

The brood pouch of seahorses can be divided into four sequential stages based on the characteristics of the altered tissue layers during gestation: the normal stage, the embryo-carrying stage, the embryo-release stage and the repair stage. The brood pouch is composed of a folded inner pseudostratified columnar epithelium and a smooth outer stratified cuboidal epithelium. Three tissue layers between the inner and the outer epithelia are an inner loose connective tissue layer, a middle smooth muscle layer and an outer dense irregular connective tissue layer. In the normal stage, the inner loose connective tissue layer is thick and vascularised with small blood vessels; the muscle layer consists of scattered unorganised muscle fibres. In the embryo-carrying stage, the inner epithelial and inner loose connective tissue layers become distended and highly vascularised with enlarged blood vessels. In the embryo-release stage, the inner loose connective tissue layer is extensively vascularised with very large blood vessels and the smooth muscle fibres invade the outer dense irregular connective tissue layer. Structures altered during gestation gradually resume their normal condition in the repair stage. Extensive vascularisation of the brood pouch during gestation suggests an intricate paternal–embryo relationship implying other significant roles besides protective function of the pouch.

Histological considerations of the cleavage plane for preservation of facial and cochlear nerve functions in vestibular schwannoma surgery

2009 ◽  
Vol 110 (4) ◽  
pp. 648-655 ◽  
Author(s):  
Tomio Sasaki ◽  
Tadahisa Shono ◽  
Kimiaki Hashiguchi ◽  
Fumiaki Yoshida ◽  
Satoshi O. Suzuki
Keyword(s):  
Connective Tissue ◽  
Basic Protein ◽  
Cleavage Plane ◽  
Nerve Fibers ◽  
Vestibular Nerve ◽  
Cochlear Nerve ◽  
Tissue Layer ◽  
Connective Tissue Layer ◽  
Tumor Capsule ◽  
Tumor Parenchyma

Object The authors analyzed the tumor capsule and the tumor–nerve interface in vestibular schwannomas (VSs) to define the ideal cleavage plane for maximal tumor removal with preservation of facial and cochlear nerve functions. Methods Surgical specimens from 21 unilateral VSs were studied using classical H & E, Masson trichrome, and immunohistochemical staining against myelin basic protein. Results The authors observed a continuous thin connective tissue layer enveloping the surfaces of the tumors. Some nerve fibers, which were immunopositive to myelin basic protein and considered to be remnants of vestibular nerve fibers, were also identified widely beneath the connective tissue layer. These findings indicated that the socalled “tumor capsule” in VSs is the residual vestibular nerve tissue itself, consisting of the perineurium and underlying nerve fibers. There was no structure bordering the tumor parenchyma and the vestibular nerve fibers. In specimens of tumors removed en bloc with the cochlear nerves, the authors found that the connective tissue layer, corresponding to the perineurium of the cochlear nerve, clearly bordered the nerve fibers and tumor tissue. Conclusions Based on these histological observations, complete tumor resection can be achieved by removal of both tumor parenchyma and tumor capsule when a clear border between the tumor capsule and facial or cochlear nerve fibers can be identified intraoperatively. Conversely, when a severe adhesion between the tumor and facial or cochlear nerve fibers is observed, dissection of the vestibular nerve–tumor interface (the subcapsular or subperineurial dissection) is recommended for preservation of the functions of these cranial nerves.

Quantitative Ultrasound Imaging of Healthy and Reconstructed Cleft Lip: A Feasibility Study

2007 ◽  
Vol 44 (3) ◽  
pp. 261-268 ◽  
Author(s):  
Nancy J. M. van Hees ◽  
Johan M. Thijssen ◽  
Rinske W. Huyskens ◽  
Gert Weijers ◽  
Maartje M. Nillesen ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Cleft Lip ◽  
Scar Tissue ◽  
Noninvasive Evaluation ◽  
Central Position ◽  
Tissue Layer ◽  
Loose Connective Tissue ◽  
Connective Tissue Layer ◽  
Array Transducer ◽  
Orbicularis Oris Muscle

Objective: To investigate the feasibility of echographic imaging of healthy and reconstructed cleft lip and to estimate tissue dimensions and normalized echo level. Methods: Echographic images of the upper lip were made on three healthy subjects and two patients using a linear array transducer (7 to 11 MHz bandwidth) and a noncontact gel coupling. Tissue dimensions were measured using calipers. Echo levels were calibrated and were corrected for beam characteristics, gel path, and tissue attenuation using a tissue-mimicking phantom. Results: At the central position of the philtrum, mean thickness (SD) of lip loose connective tissue layer, orbicularis oris muscle, and dense connective layer was 4.0 (0.1) mm, 2.3 (0.7) mm, and 2.2 (0.7) mm, respectively, in healthy lip at rest; and 4.1 (0.9) mm, 3.8 (1.7) mm, and 2.6 (0.6) mm, respectively, in contracted lip. Mean (SD) echo level of muscle and dense connective tissue layer with respect to echo level of lip loose connective tissue layer was −19.3 (0.6) dB and −10.7 (4.0) dB, respectively, in relaxed condition and −20.7 (1.5) dB and −7.7 (2.3) dB, respectively, in contracted state. Color mode echo images were calculated, showing lip tissues in separate colors and highlighting details like discontinuity of the orbicularis oris muscle and presence of scar tissue. Conclusions: Quantitative assessment of thickness and echo level of various lip tissues is feasible after proper echographic equipment calibration. Diagnostic potentials of this method for noninvasive evaluation of cleft lip reconstruction outcome are promising.

A histological and histochemical study of the development of the amnioallantois in the chick, Gallus domesticus

1970 ◽  
Vol 48 (5) ◽  
pp. 1079-1086 ◽  
Author(s):  
T. P. Kenny ◽  
M. A. Gibson
Keyword(s):  
Connective Tissue ◽  
Incubation Period ◽  
Histochemical Study ◽  
Secretory Granules ◽  
Lymphatic Vessels ◽  
Muscle Layer ◽  
Peak Activity ◽  
Tissue Layer ◽  
Connective Tissue Layer ◽  
Period 2

The amnioallantoic membrane is composed of four layers. (1) An inner amnionic epithelium which is a stratified layer during most of the incubation period. This layer stains positively for glycogen, ribonucleic acid, and neutral and acidic lipids and appears to be most active during the 15 to 17 days of incubation period. (2) A muscle layer composed of dorsoventrally and anteroposteriorly directed bands. During the early incubation stages these bands are organized to form the muscle configurations known as "cross-figures." During the later incubation stages, the organization of these muscle layers is disrupted by invasions of connective tissue and fat. (3) A connective tissue layer which includes blood and lymphatic vessels. (4) An outer allantoic epithelium which is rich in secretory granules. These granules include a sulfated mucopolysaccharide component. The activity of the allantoic epithelium increases progressively during the incubation period and is at peak activity at the 17- to 19-day incubation stage. During the final stages of incubation all layers show signs of decreased activity and degeneration.

A Comparative Histological Study of the Tube-feet of two Regular Echinoids

1961 ◽  
Vol s3-102 (58) ◽  
pp. 157-180
Author(s):  
DAVID NICHOLS
Keyword(s):  
Connective Tissue ◽  
Respiratory Function ◽  
Histological Study ◽  
Disk Surface ◽  
Goblet Cells ◽  
Sensory Cells ◽  
Muscle Fibres ◽  
Connective Tissue Sheath ◽  
Tube Feet

The histology of the suckered and peristomial tube-feet of the two regular echinoids Cidaris cidaris (Cidaroida) and Echinus esculentus (Diadematoida) is described; of these orders the Cidaroida is the more primitive. The suckered tube-feet of both urchins have a connective-tissue sheath the fibres of which branch extensively before inserting at the disk, and in which are embedded numerous spicules, enlarged distally to form a supporting skeleton of the disk. A series of levator muscles, separate from the retractors of the stem, raise the centre of the disk during adhesion, and this activity also probably squeezes mucus from a series of glands opening at the disk surface. In Cidaris a second series of glands, goblet cells in the disk epithelium, are operated by special short muscle-fibres running between them; these cells and the muscles are absent in Echinus. In Cidaris sensory cells are apparently scattered over the entire disk surface, whereas in Echinus they appear to be mainly concentrated in a ring round the disk periphery. The peristomial tube-feet of both urchins are not suckered; the levator muscles are absent, and the disk, supported by a less complex calcareous skeleton, contains mainly sensory cells and mucous glands. The possible derivation of the diadematoid, clypeasteroid, and spatangoid tube-foot plans from that of the cidaroid is discussed. The differences in ornamentation of the regions of the test which bear the tube-feet are discussed functionally, the main conclusion being that a tube-foot whose activity is at all angles to the test requires a wider base than one whose activity is mainly perpendicular; this is shown to be the case in spatangoids also. A respiratory function for Stewart's organs in the Cidaroida is suggested.

The accumulation of ferric iron in the guts of some spatangoid echinoderms

1980 ◽  
Vol 60 (3) ◽  
pp. 631-640 ◽  
Author(s):  
J. B. Buchanan ◽  
B. E. Brown ◽  
T. L. Coombs ◽  
B. J. S. Pirie ◽  
J. A. Allen
Keyword(s):  
Connective Tissue ◽  
Ferric Iron ◽  
Dry Weight ◽  
Iron Deposit ◽  
Tissue Layer ◽  
Intestinal Tissue ◽  
Connective Tissue Layer ◽  
Ferrous Salt ◽  
Ferric Phosphate ◽  
Reducing Conditions

The connective tissue layer of the large intestines of Brissopsis and Echinocardium spp. is shown to contain a massive quantity of ferric iron in the form of ferric phosphate. The ferric phosphate is present as a granular extracellular deposit. In large mature specimens of Brissopsis, the weight of iron present may account for almost 30% of the dry weight of large intestinal tissue. The iron deposit appears to be cumulative with age. It is speculated that the deposit is derived from oxidative deposition of a soluble ferrous salt ingested in reducing conditions.

Innervation of cat iris dilator

1964 ◽  
Vol 207 (6) ◽  
pp. 1411-1416 ◽  
Author(s):  
U. Schaeppi ◽  
W. P. Koella
Keyword(s):  
Electrical Stimulation ◽  
Adrenergic Receptors ◽  
Isometric Tension ◽  
Adrenergic Nerve ◽  
Nerve Terminals ◽  
Beta Adrenergic Receptors ◽  
Dilator Muscle ◽  
Adrenergic Nerve Terminals ◽  
Electrical Stimuli

Isometric tension changes of radially oriented iris strips of the cat were investigated in vitro. Electrical stimulation, norepinephrine (NE), and tyramine elicited contraction whereas isoproterenol elicited relaxation. Phentolamine reduced electrically and NE induced contractions and, in large doses, converted them to relaxation. Dichloroisoproterenol decreased this relaxation and the relaxation induced by isoproterenol. After chronic sympathetic denervation, electrical stimuli induced mainly relaxation and tyramine had no effect. These results indicate that contractions and relaxations in normal preparations are preponderantly mediated via excitation of adrenergic nerve terminals and release of adrenergic transmitter acting upon alpha and beta adrenergic receptors, respectively. Neostigmine and atropine had little effect on the electrically induced effects of normal preparations. In chronically denervated dilator strips, neostigmine increased and atropine decreased the relaxations and occasional slight contractions produced by electrical stimuli. These observations are interpreted that cholinergic relaxation mechanisms are also involved in the control of the dilator muscle, and that cholinergic contractions are due to activation of aberrant sphincter fibers contaminating the dilator muscle.

Squid mantle muscle

1981 ◽  
Vol 61 (2) ◽  
pp. 327-342 ◽  
Author(s):  
Q. Bone ◽  
A. Pulsford ◽  
A. D. Chubb
Keyword(s):  
Connective Tissue ◽  
Central Zone ◽  
Circular Muscle ◽  
Fibre Types ◽  
Power Stroke ◽  
Muscle Fibres ◽  
Nerve Terminals ◽  
Vascular Bed

The mantles of the small squid Alloteuthis, the larger Loligo, and the cuttlefish Sepia contain an elaborate framework of connective tissue fibres running in different planes. Some of these fibres are apparently elastic. The circular muscle fibres which provide the power stroke in mantle contraction are of two types. Inner and outer mantle zones consist of well-vascularized mitochondria-rich fibres, whereas the central zone contains only mitochondria-poor fibres with a sparse vascular bed. Nerve terminals on the two fibre types are similar. The radial fibres opposing the circular fibres are of the same type as the central fibres, at least in the mid-region of the mantle. It is suggested that the central fibres are involved in escape jetting contractions, and that the fibres of the inner and outer zones are used during rhythmical respiratory contractions.

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