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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 352 (1974), S. 1-10 
    ISSN: 1432-2013
    Keywords: Thermoreceptors ; Cold Receptor ; Ultrastructure ; Receptor Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Afferent impulses were recorded from single fibers serving cold and warm receptors in the skin of the cat's nose. The receptors were carefully tested for specificity and the receptive fields localized under the microscope with a microthermode. Each single fiber served one spot-like receptive field. The field was marked without damaging the nerve ending by inserting two thin stainless steel wires into the skin on both sides of the receptor. Investigation of semithin and ultrathin serial sections by light and electron microscopy revealed beneath each cold spot a dermal papilla which contained a single small myelinated fiber dividing into a number of unmyelinated terminals. Near the epidermis the receptor branches leave their Schwann cell envelope, penetrate the basal lamina of the epithelium, and their tips are invaginated into the cytoplasm of the basal epithelial cells. The basal lamina of the epithelium fuses with that of the receptor axon. The receptor axons contain numerous mitochondria, glycogen particles and a filamentous receptor matrix with vesicles of various sizes. The described structures were absent beneath the warm spots. In addition to the cold receptors, Merkel cell neurite complexes and lamellated encapsulated endings were found that are known to be mechanoreceptors.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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