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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 172 (1985), S. 145-156 
    ISSN: 1432-0568
    Keywords: Afferent nerve fiber ; Nociceptor ; Sensory terminal ; Tendon innervation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In sympathectomized cats the innervation of the Achilles tendon by fine afferent nerve fibers was studied with semithin and ultrathin sections. Several different types of sensory endings of group III and group IV nerve fibers were identified. Of the five different types of endings in the group III range (T III endings), two are located within vessel walls. One of them ends in the circumference of the venous vessels (T III/VV). Its lanceolate terminals have characteristic receptor areas at their edges. The second type ends in the adventitia of lymphatic vessels (T III/LV). Its receptive areas are scattered along their terminal course. Two further group III endings ramify within the connective tissue compartments of the vessel-nerve-fascicles of the peritenonium externum and internum. One type is tightly surrounded by collagen fibrils (T III/PTic); the other terminates between the collagen fiber bundles (T III/PTgc). The latter arrangement recalls the ultrastructural relation between nerve terminals and collagen tissue in Golgi tendon organs. The fifth type innervates the endoneural connective tissue of small nerve fiber bundles (T III/EN). At least some of them come into close contact with bundles of collagen fibers which penetrate the perineural sheath to terminate within the endoneurium. The endings of group IV afferents (T IV endings) show a striking topographic relationship to the blood and lymphatic vessels of all connective tissue compartments of the Achilles tendon. They form penicillate endings which may contain granulated vesicles. In any event, they can easily be discriminated from the T III endings in the vessel walls. In close neighborhood to Remak bundles, a cell has been regularly found which fulfilled all ultrastructural criteria for mast cells. But this cell is not a mast cell proper because it is surrounded by a basal lamina (pseudo mast cell).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 172 (1985), S. 133-143 
    ISSN: 1432-0568
    Keywords: Wallerian degeneration ; Muscle nerve ; Postganglionic nerve fiber ; Ramus communicans griseus ; Sympathectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cats the time course of degeneration following lumbal sympathectomy was studied in the ramus communicans griseus (reg) and in the nerves to the triceps surae muscle using light and electron microscopic methods. The left lumbar sympathetic trunk including its rami communicantes was removed from L2 to S1 using a lateral approach. The animals were sacrificed between 2 and 48 days after the sympathectomy. Tissue samples were taken (a) one cm proximal to the entrance of the rcg into the spinal nerve, and (b) one cm proximal to the entrance of the nerve into the muscle belly. In the reg signs of degeneration can already be recognized in the myelinated as well as in the unmyelinated axons 48h after sympathectomy. The degenerative processes in the axons reach their peak activity at about 4 days p.o. They end a weck later. Signs of the reactions of the Schwann cells and of the endoneural cells can first be seen 2 days p.o. They are most pronounced around the 8th day p.o., and last at least up to the third week. Thereafter the cicatrization processes settled to a rather steady state (total observation period 7 weeks). In the muscle nerves the first signs of an axonal degeneration of the sympathetic fibers can be recognized 4 days after surgery. The signs of axonal degeneration are most striking about 8 days p.o. They have more or less disappeared another week later. The reactions of the Schwann cells also start on the fourth day but outlast the degenerative processes by some 8 days. Thus the degenerative and reactive processes in the reg precede those in the muscle nerves by 2 days early after surgery and by 6 days 3 weeks later. Seven weeks after surgery, fragments of folded basement lamella and Remak bundles with condensed cytoplasm and numerous flat processes are persisting signs of the degeneration. In addition to the differences in time course between the proximal and the distal site of observation, it was also noted that both the axonal degeneration and the reactions of the Schwann cells are more pronounced in the rcg than in the muscle nerve. For example there was abundant mitotic activity in the central endoneural and Schwann cells whereas we could not detect such activity in the periphery. It is concluded that the time course of degeneration and the intensity of the degenerative and reactive processes is, to a considerable extent, determined by the distance between the site of nerve section and the site from which the specimen is taken. Many of the conflicting data in the literature can be explained by this finding.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0568
    Keywords: Ampullary electroreceptor ; Tuberous electroreceptor ; Sensory innervation ; Scanning and transmission electronmicroscopy ; Pseudocetopsis spec. (catfish)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two types of electroreceptors, the ampullary and the tuberous electroreceptor (silurid knollenorgan) in the epidermis of the catfish, Pseudocetopsis spec., were investigated with semithin and ultrathin serial sections. The ampullary organ contains one or two sensory cells which are embedded in supporting cells at the base of open epithelial canals. They bear some slender microvilli on their apical surface and form several synaptic bars. The afferent myelinated nerve fiber arborizes in the connective tissue papilla and looses its myelin sheath about 30 μm below the supporting cell layer. A second thin myelinated axon occur up to the supporting cell layer. The tuberous electroreceptor organ contains one large receptor cell. Most of the cell body is exposed to the lumen of a specialized proximal canal segment and is closely covered with microvilli. A single myelinated axon looses its myelin sheath within the supporting cell layer about 1 μm before terminating as a flat calyx at the base of the sensory cell. A functional significance of the two types of receptors will be discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 175 (1987), S. 289-301 
    ISSN: 1432-0568
    Keywords: Dura mater encephali ; Sensory receptors ; Nerve fibres ; Vascular bed ; Lymphatic vessel ; Nociception ; Headache
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The dura mater encephali of the rat is richly supplied by myelinated (A-axons) and unmyelinated (C-axons) nerve fibres. For the supratentorial part the main nerve supply stems from all three branches of the trigeminal nerve. Finally, 250 myelinated and 800 unmyelinated nerve fibres innervate one side of the supratentorial part. The vascular bed of the dura mater exhibits long postcapillary venules up to 200 μm in length with segments of endothelial fenestration. Lymphatic vessels occur within the dura mater. They leave the cranial cavity through the openings of the cribriform plate, rostral to the bulla tympani together with the transverse sinus, and the middle meningeal artery. The perineural sheath builds up a tube-like net containing the A- and C-axons. It is spacious in the parietal dura mater and dense at the sagittal sinus along its extension from rostral to caudal and at the confluence of sinuses. Terminals of both the A- and C-axons are of the unencapsulated type. Unencapsulated Ruffini-like receptors stemming from A-axons are found in the dural connective tissue at sites where superficial cerebral veins enter the sagittal sinus and at the confluence of sinuses. The terminations of single A-axons together with C-fibre bundles mix up in their final course in one Schwann cell to build up multiaxonal units or terminations (up to 15 axonal profiles). A morphological differentiation is made due to the topography of these terminations; firstly, in different segments of the vascular bed: postcapillary venule, venule, the sinus wall, lymphatic vessel wall, and secondly, within the dura mater: inner periosteal layer, collagenous fibre bundles of the meningeal layer and at the mesothelial cell layer of the subdural space.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report the first measurements of the magnetic-field penetration depth λ in the heavy electron superconductor UBe13, performed using a SQUID magnetometer. We find the temperature dependence of λ(T)-λ(0) to follow aT 2 law at low temperatures, giving further evidence of extreme gap anisotropy in this compound. We calculate the temperature dependence expected for a variety of anisotropic states, including those representing certain classes of “exotic” pairing. In general situations, the supercurrent is not parallel to the vector potential, and a more complicated field penetration takes the place of the normal Meissner effect. We argue that the data are consistent with an energy gap with point nodes on the Fermi surface but inconsistent with the large value of the Landau parameterF 1 S expected for a translationally invariant Fermi liquid with large effective mass.
    Type of Medium: Electronic Resource
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