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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 59 (1978), S. 7-11 
    ISSN: 1432-2072
    Schlagwort(e): Concurrent schedule ; Ethanol drinking ; Water drinking ; Food deprivation ; Food satiation ; Ethanol concentration ; Rats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Dippers filled with water or an ethanol solution were presented to male Wistar rats contingent on lever-pressing under a concurrent fixed-ratio 1 (water) fixed-ratio 1 (ethanol) schedule. During Phase I, when maintenance feedings were given during instead of following the daily 3-h sessions, the feedings increased drinking of both 8% (w/v) ethanol and water, with 8% ethanol being consumed in greater volumes than water. In Phase II, a 28-day transitional period from the food-deprived to the food-satiated state, continuous access to food during 3-h sessions moderately decreased 8% ethanol intake, and increased water intake and total liquid intake (water plus 8% ethanol). In Phase III, concurrent water and ethanol intake of food-satiated rats was compared over two identical series of ethanol concentrations (8, 11.3, 16, 22.6, 32, and 8% retest). Food was freely available in both the operant conditioning chambers and home cages. The number of dipper presentations of ethanol exceeded presentations of water for each rat at each concentration studied. Presentations of water were low in number and did not vary with the ethanol concentration. As the ethanol concentration was increased, the number of ethanol presentations decreased, while the quantity consumed (mg/100 g body weight/h) generally increased.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 57 (1978), S. 133-136 
    ISSN: 1432-2072
    Schlagwort(e): Rhesus monkeys ; Ethanol reinforcement ; Ethanol concentration ; Blood ethanol level ; Ethanol drinking ; Fixed-ratio schedules ; Intoxication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Ethanol deliveries maintained fixed-ratio (FR) responding of three rhesus monkeys during daily 3-h sessions. At FR values of 8 or 16, ethanol concentration was varied in the sequence 0 (water), 8, 11.3, 16, 22.6, 32, 8, and 0% (w/v). As the ethanol concentration increased, number of liquid deliveries decreased, although intake of ethanol (g/kg/session) increased somewhat. Blood ethanol levels were usually greater than 200 mg% and occasionally greater than 300 mg%.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 453-473 
    ISSN: 1432-0878
    Schlagwort(e): Metamorphosis ; Settlement ; Morphogenetic movements ; Adhesive organs ; Ascidians
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cup-shaped adhesive papillae of Distaplia occidentalis evert at the onset of metamorphosis and each transforms into a hyperboloidal configuration. The rate of transformation is a function of temperature. At 14° C complete eversion takes about 30 seconds. Myoepithelial cells that extend from the rim to the base on the cup contract. Simultaneously the central part of the papilla advances 60–70 μm. During the last phases of eversion, collocytes (cells that secrete adhesives) on the inner wall of the cup and on the sides of the axial protrusion flow outward and form a collar-like structure. The myoepithelial cells contain arrays of thick and thin filaments. These become compacted during contraction. The surfaces of these cells become extensively folded as they shorten to about 1/3 of rest length. According to the proposed model the myoepithelial cells are the driving force in papillary eversion. Immediately after eversion is completed the papillae begin to retract. Eversion of the papillae is not inhibited by cytochalasin B, but the process of retraction is reversibly inhibited. Some histological characteristics of five types of everting papillae in four families of ascidians are compared.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 183 (1977), S. 423-444 
    ISSN: 1432-0878
    Schlagwort(e): Ascidian larva ; Adhesive papillae ; Settlement ; Myoepithelial cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The larva of Distaplia occidentalis bears three cup-shaped adhesive papillae, each with a prominent axial protrusion. At the onset of metamorphosis these organs rapidly evert through fenestrations in the cuticular layers of tunic exposing hyaline caps of adhesive. Additional adhesive material is secreted from collocytes during eversion. The stickiness of the papillae facilitates attachment to a variety of substrates. Each papilla is composed of more than 900 cells; six different types were identified. The wall of the cup contains about 260 myoepithelial cells with long attenuated processes. These extend from the rim of the cup to the base in the parietal (inner) layer. The apices of the myoepithelial cells are held in place by 11 pairs of specialized anchor cells bearing long bulbous microvilli. When the myoepithelial cells contract they force the axial protrusion forward and transform the papilla into a hyperboloidal configuration. The papilla is innervated by small motor fibers, but sensory fibers were not detected. The adhesive papillae of Distaplia are discussed in relationship to nine other recognizable types of papillae in the ascidians.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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