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  • 1
    Digitale Medien
    Digitale Medien
    Blood vessels and the occurrence of arteriovenous anastomoses in cephalic heat loss areas of mallards, Anas platyrhynchos (Aves) (1984)
    Springer
    Zoomorphology 104 (1984), S. 323-335 
    Details
    ISSN: 1432-234X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 1. The blood supply to cephalic heat loss areas (nasal and oropharyngeal mucosa, bill, eyelids) was studied in mallards by using plastic corrosion casts. The structure and organization of the blood vessels, as well as the occurrence of arteriovenous anastomoses (AVAs), were examined by scanning electron microscopy of vascular casts and by paraffin sections. 2. Submucosal venous plexuses (cavernous tissue) are present in the nasal cavity, tongue, and lateral margins of the palate. These plexuses receive blood from post-capillary venules, but may also receive a non-nutritive component via numerous AVAs. 3. High densities of AVAs were found in the eyelids and in the tip of the bill. In the tongue and nasal mucosa, the AVAs decreased in number caudally. The reason for regional differences in the density of AVAs is discussed in relation to variation in mechanical and thermal stimulation of the tissues. 4. The connection of the different heat loss areas with the Rete ophthalmicum, which is a countercurrent heat exchanger important for brain cooling, is pointed out. The vascular pattern of the head suggests that sphincteric veins are involved in regulating the venous return from the evaporative surfaces of the nasal cavity and palate. One of these veins had, in addition to the normal circular smooth muscle fibres, a conspicuous component of longitudinally arranged, subendothelial, smooth muscle fibres.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00312014
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Arteriovenous anastomoses and vascularity in the feet of eiders and gulls (Aves) (1980)
    Springer
    Zoomorphology 96 (1980), S. 263-270 
    Details
    ISSN: 1432-234X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Arteriovenous anastomoses (AVAs) and vascularity were studied in the webbed feet of eiders and two species of gulls using an injection technique. The density of AVAs was high in the distal part of the web (85–126 AVAs per cm2) and decreased proximally. Anastomoses were also present in the feathered skin of the tibiotarsus (18–39 AVAs per cm2). A positive correlation was found between the density of AVAs and the vascularity of the skin. The role of the AVAs in temperature regulation is briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00310291
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Innervation of arteriovenous anastomoses in the brood patch of the domestic fowl (1988)
    Springer
    Cell & tissue research 252 (1988), S. 207-210 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Brood patch ; Arteriovenous anastomoses ; Innervation ; Vasoactive intestinal polypeptide (VIP) ; Domestic fowl
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The innervation of blood vessels in the brood patch (thoracic skin) of the domestic fowl was studied by use of the catecholamine fluorescence technique, acetylcholinesterase staining, and the immunoperoxidase technique for demonstration of vasoactive intestinal polypeptide (VIP). Large arteries and veins were sparsely innervated, whereas arteriovenous anastomoses (AVAs) were densely innervated by adrenergic, acetylcholinesterase-positive, and VIP-immunoreactive nerve fibres. The rich supply of different vasomotor nerves to AVAs emphasizes the importance of these vascular shunts in regulating blood flow and, in turn, the transport of heat to the brood patch. Furthermore, the presence of VIP-immunoreactive nerve fibres in the vasculature of the brood patch suggests that VIP might be the mediator of the previously reported cold-induced vasodilatation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00213843
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Blood flow in the brood patch of Bantam hens: evidence of cold vasodilatation (1985)
    Springer
    Journal of comparative physiology 155 (1985), S. 703-709 
    Details
    ISSN: 1432-136X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. Blood flow was measured in the brood patch of Bantam hens by recording the washout of133Xe from the tissue in different experimental conditions. 2. In hens incubating 5 eggs at normal temperature, cutaneous and subcutaneous blood flow in the brood patch averaged 0.31 ml·min−1·g−1 and 0.15 ml·min−1·g−1, respectively. 3. Cooling the brood patch in restrained hens immediately increased cutaneous and subcutaneous blood flow by an average of 83% and 63%, respectively. The increase in blood flow was restricted to the site of cooling, while neighbouring skin areas showed little change in flow. This cold vasodilatation could also be elicited in hens incubating water circulated eggs and was unaffected by local anaesthetics. 4. The observations suggest that the vasodilatation in response to cooling is due to a direct temperature influence on the smooth muscle cells of the brood patch vasculature. 5. It is suggested that the cold vasodilatation may be important for providing increased heat transfer to the eggs at low ambient temperatures or when the parent bird returns to cool eggs after feeding excursions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00694584
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Therete ophthalmicum and the relation of its size to the body-to-brain temperature difference in the fowl (Gallus domesticus) (1983)
    Springer
    Journal of comparative physiology 153 (1983), S. 241-246 
    Details
    ISSN: 1432-136X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. Hypothalamic and body temperatures were measured in eight domestic fowls (Gallus domesticus) at an ambient temperature of 26°C and subsequently the functional anatomy of therete ophthalmicum was examined. Individual differences in brain cooling were compared to the size of the rete and other morphological parameters. 2. The total number of arteries and veins in the rete was 59.3±9.7 and 41.5±6.5 (mean±SD), respectively, and the maximum area available for countercurrent heat exchange could be described by a power function of body weight. 3. The body-to-brain temperature difference was significantly correlated to the exchange area of the rete (r=0.82, 0.01〈P〈0.02), but not to other morphological parameters such as size of comb, skull thickness, and palate area. 4. This study shows that the exchange area of therete ophthalmicum is an important parameter which determines the efficiency of brain cooling, and that individual differences in the body-to-brain temperature difference may be explained by differences in the size of the heat exchanger.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689627
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Brain temperature and therete mirabile ophthalmicum in the Zebra finch (Poephila guttata) (1981)
    Springer
    Journal of comparative physiology 145 (1981), S. 89-93 
    Details
    ISSN: 1432-136X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. Brain and colonic temperatures were measured in five Zebra finches (Poephila guttata) with a mean body weight of 0.013 kg. 2. The mean body-to-brain temperature difference (0.18 °C) was lower than in all other previously studied species of birds, indicating a decreased ability to cool the brain in the Zebra finch. 3. Morphological studies of the head vasculature revealed that therete mirabile ophthalmicum was very simple. The absence of a well-developed rete is presumed to be responsible for the decreased ability of brain cooling. 4. The present study may provide a clue to the well known phenomenon of mass death among small birds during periods with extreme ambient temperatures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00782598
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    The blood vascular system in the head of the herring gull (Larus argentatus) (1984)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 135-152 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure and development of the blood vascular system in the head of the herring gull (Larus argentatus) have been studied using injection techniques and histological sections. Three different but interconnected divisions of the arterial system are recognized in the adult: the cerebral carotid artery system, the external ophthalmic artery system, and the external carotid artery system. Embryologically, the arterial system is characterized by changes in the relative development of these three divisions; the cerebral carotid system being the most prominent in the first half of the embryonic period. The venous system is divided into two parts, the rostral cephalic system and the caudal cephalic system, which drain separate regions of the head. The Rete ophthalmicum, which is an arteriovenous network associated with the external ophthalmic artery system, can be identified from the fifth day of incubation, and its development appears to be coupled with changes in the arterial supply to the eye. The possibility of a homology between the Rete ophthalmicum of birds and the Rete caroticum of mammals is briefly discussed.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051790203
    Standort Signatur Erwartet Verfügbarkeit
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