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  • 1
    Electronic Resource
    Electronic Resource
    Structural and ultrastructural features of the inlet and outlet regions of the urinary bladders of the leech, Hirudo medicinalis L. (1989)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 201 (1989), S. 285-291 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each of the 34 nephridia in the leech, Hirudo medicinalis, has its own separate bladder. Urine flows from the last portion of the nephridium, the final canal, into the bladder through a special inlet which prevents backflow of urine. This inlet consists of a vestibule formed by two serially arranged septa, each with a small pore. As no muscles or cilia are associated with either the nephridia or the bladder inlet, urine flow into the bladder is passive. Urine leaves the bladder through an outlet that consists of a urethra with sphincters at both ends and an opening, the nephridiopore, in the ventral skin. The sphincter muscles are distinct from the body wall muscles and receive double innervation: urine retention and release is therefore active.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052010307
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructure of sea urchin tube feet (1977)
    Springer
    Cell & tissue research 177 (1977), S. 195-214 
    Details
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Connective tissue ; Echinoderms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An analysis of the ultrastructure of the tube feet of three species of sea urchins (Strongylocentrotus franciscanus, Arbacia lixula and Echinus esculentus) revealed that the smooth muscle, although known to be cholinoceptive, receives no motor innervation. The muscle fibers are attached to a double layer of circular and longitudinal connective tissue which surrounds the muscle layer and contains numerous bundles of collagen fibers. On its outside, the connective tissue cylinder is invested by a basal lamina of the outer epithelium to which numerous nerve terminals are attached. These are part of a nerve plexus which surrounds the connective tissue cylinder. The plexus itself is an extension of a longitudinal nerve that extends the whole length of the tube foot. It is composed of axons, but nerve cell bodies and synapses are conspicuously lacking, suggesting that the axons and terminals derive from cells of the radial nerve. Processes of the epithelial cells penetrate the nerve plexus and attach to the basal lamina. There is no evidence that the epithelial cells function as sensory cells. On the basis of supporting evidence it is suggested that the transmitter released by the nerve terminals diffuses to the muscle cells over a distance of several microns and in doing so affects the mechanical properties of the connective tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221081
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Nephridial innervation in the leech Hirudo medicinalis L. (1986)
    Springer
    Cell & tissue research 245 (1986), S. 397-404 
    Details
    ISSN: 1432-0878
    Keywords: Leech ; Nephridium ; Innervation ; Electron microscopy ; Cobalt filling ; Hirudo medicinalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The main organs for salt and water homeostasis in the medicinal leech, the nephridia, were found to be densely innervated by a single branch of the corresponding median anterior segmental nerve. The projections of two different neurons into the nephridia are described: 1. Dendritic projections of the previously identified, afferent ‘nephridial nerve cell’, a possible salt receptor, lie between the urine forming cells and the blood vessels supplying the nephridium without making any contact. 2. Projections of an unidentified neuron which contains dense-core vesicles (85 nm) as well as smaller clear vesicles (45 nm) contact the primary urine forming canaliculus cells. The neurosecretory role of these neurons is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213947
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    Paper (German National Licenses)
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