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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 154 (1977), S. 95-113 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The origin, distribution and structure of the blood vessels of the female reproductive tract and the testis of the brush possum (Trichosurus vulpecula) were studied using latex and silicone rubber casting and histological techniques. Latex casts of the vessels of the female tract were also studied in five macropod species - Macropus giganteus, M. eugenii, M. agilis, Megaleia rufa and Thylogale billardierii, and in the common wombat (Vombatus ursinus).The female reproductive tract in the brush possum was supplied and drained by four major sets of paired vessels - ovarian, cranial urogenital, caudal urogenital, and internal pudendal arteries and veins. These vessels formed substantial anastomoses with one another on each side of the midline, and also across-the-midline anastomoses. The proximal part of the ovarian artery ran in close apposition to the ovarian vein, which received one or more large uterine branches. In its distal protion the ovarian artery gave rise to a leash of small, tortuous ovarian branches, which wound around and between the plexiform ovarian veins.The testicular arteries and veins in this species also ran in close apposition to one another. Both arteries and veins branched into many smaller, mildly tortuous, parallel vessels in the spermatic cord, which reunited before entering the testis.The blood vessels of the reproductive tract in all of the macropod species studied, and in the common wombat, were basically similar to those of the brush possum.The intimate structural relationships between ovarian arteries and veins, and their ovarian branches, in these marsupials are suggestive of specializations for counter-current exchange between venous and arterial blood. However, in contrast to those of the testicular vessels where heat exchange is a demonstrated function, their physiological significance remains unknown.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 148 (1976), S. 287-303 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The extrinsic ovarian blood vessels were studied in 134 ewes. In view of recent evidence that uterine luteolysis may involve local veno-arterial transfer of prostaglandin F2α in the ovarian pedicle, particular attention was paid to the interrelationships between veins and arteries.The ovarian artery and utero-ovarian vein are large vessels of conventional structure and lie in close apposition. Their walls are slightly thinner on their apposing sides. The ovarian branches of the ovarian artery are very tortuous, and closely intertwined with the plexiform ovarian branches of the utero-ovarian vein.An extensive plexus of small veins surrounds the ovarian artery and its ovarian branches. Within this plexus are many thin-walled, dilated regions, interspersed with narrow, thick-walled segments. Valves are inconstantly present at sites of entry of branches of the plexus into the major veins. Small numbers of arterio-venous anastomoses are present in the distal part of the ovarian pedicle.Unless blood can flow in a veno-arterial direction through arterio-venous anastomoses or capillary beds, the structural barrier between uterine venous and ovarian arterial blood is substantial.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 126 (1969), S. 489-495 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Six multiparous ewes, three of which were lactating and the remaining three in an advanced stage of mammary involution, were used to study the distribution of lymphatic vessels in the mammary gland. The lymphatic system was distended by ligation of the regional efferent lymphatic ducts and either reconstituted blood or Latex was used to fill the blood vascular system. After fixation, distribution of lymphatic vessels was studied macroscopically and microscopically.One to three mammary nodes were situated at the postero-dorsal aspect of each gland. Entering and leaving the nodes were 8 to 12 major afferent and 2 to 4 efferent ducts. Four or five of the afferent ducts accompanied the external pudendal artery and vein and their radicles emerged from the deep parenchyma of the gland. The remaining afferent ducts emerged from the parenchyma of the gland independent of blood vessels and their radicles drained both superficial and deep parenchyma.Lymphatic vessels were found in the connective tissue between lobes, within lobes and between lobules. Lymphatic capillaries were observed in the connective tissue within lobules and also in areas adjacent to the alveolar epithelium. Lymphatic vessels in the connective tissue between lobes and the larger vessels were supplied with valves and their walls posessed an endothelial cell lining together with smooth muscle and connective tissue layers. Finer lymphatic vessels appeared to consist of only a simple endothelial cell lining and valves were not found.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 26 (1998), S. 200-212 
    ISSN: 1573-9686
    Keywords: Aortic bifurcation ; Atherosclerosis ; Wall shear stress ; Vasoactive drugs ; Phase angle ; Abdominal aorta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The present study compares the wall shear stress (rate) distribution in a compliant aortic bifurcation model under three different hemodynamic states: normal state, angiotensin II infusion state (vasoconstrictor), and isoproterenol infusion state (vasodilator). Using a Newtonian blood analog fluid, flow wave forms corresponding to each flow state were generated in an in vitro flow loop and a photographic flow visualization technique was employed to measure wall shear rate. The results indicate a zone of low mean wall shear stress and highly oscillatory shear stress on the outer (lateral) wall of the bifurcation. In this zone, the mean wall shear stress became negative for all three hemodynamic states indicating flow separation. However, the spatial extent of the flow separation zone was not affected significantly by the flow state. The study also revealed a large spatial variation of the phase angle between the hoop strain (circumferential strain due to radial artery expansion) and the wall shear stress, the two main mechanical stimuli acting on endothelial cells which affect their biology. In the zone of low mean wall shear stress on the outer wall, the two stimuli were more out of phase relative to the mother branch, whereas they were less out of phase (by about 50°) on the inner wall (flow divider side). This phase angle was affected significantly by the flow state. For angiotensin II, the phase angle reached a maximum of 125° in the low mean shear zone while the maximum was 94° and 66° for the normal and isoproterenol states, respectively. Our observation that large phase angles between the hoop strain and wall shear stress wave forms are localized in the low shear stress region where atherosclerotic disease occurs suggests the possible physiological relevance of this phase angle to the development of atherosclerosis. © 1998 Biomedical Engineering Society. PAC98: 8745Hw
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 22 (1994), S. 371-380 
    ISSN: 1573-9686
    Keywords: Valve closure ; Tilting disc valve ; Peripheral clearance ; Instantaneous back flow ; Computational fluid dynamic analysis ; Wall shear stress ; Pressure ; Cavitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract An investigation of the flow dynamics through the peripheral clearance (the gap formed between the occluder tip and the metal housing in the closed position) of a tilting disc heart valve at the moment of valve closure is presented. A Medtronic Hall valve in the mitral position of anin vitro experimental set up is employed to measure the transient pressure pulses near the entrance (ventricular side) and exit (atrial side) of the peripheral clearance at valve closure. Flow within the peripheral clearance is analyzed employing a two-dimensional quasisteady computational fluid dynamics model with the measured peak pressures specified as the boundary conditions inducing the flow. The valve is visualized from its inflow (atrial) side using a stroboscopic lighting technique to investigate the presence of cavitation bubbles within the clearance. The pressure measurements showed that a relatively large pressure drop exists between the entrance and the exit to the clearance for about 0.5 msec at the moment of valve closure. The numerical simulation resulted in relatively large magnitudes of wall shear stress and pressure reduction within the clearance due to the flow established by the large pressure drop between the entrance and the exit. Cavitation bubbles visualized within the peripheral clearance at higher loading rates for valve closure correlated with the presence of large pressure reduction within the clearance. Analysis of the results of this study indicates that the back flow through the clearance at the instant of valve closure may contribute toward injury to formed elements in blood in spite of the short duration of the flow.
    Type of Medium: Electronic Resource
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