ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The intraarterial cushions present in the rat at the points of branching of the main uterine artery have been studied by means of scanning electron microscopy. Such studies confirmed the three-dimensional concept of these structures gained from previous light microscopic serial section reconstructions as incomplete, raised, asymmetric ridges which encompass the branch orifice. The examination of methacrylate corrosion casts of the uterine vasculature with the scanning electron microscope provided a means for evaluating the relative protrusion or retraction of the cushion structures within the vessel lumen, and thus for assessing their role in regulating uterine blood flow in various physiologic states. Cushions were studied in this manner at the stages of the estrous cycle, in castrated animals, and in animals receiving pharmacologic doses of an alpha adrenergic agonist, phenylephrine. Evaluation of the relative depth of the impression left upon the vascular casts by cushions permitted the following conclusions. The cushions protruded maximally (and thus impeded flow most effectively) in castrated animals and in animals treated with the vasoconstrictor, phenylephrine. In contrast, the cushions protruded less in animals in proestrus and estrus. These data suggest that the cushions do respond, either actively, by virtue of the contractile state of the smooth muscle within the cushion, or passively, as a function of overall vessel geometry, to alpha adrenergic stimulation. The contrast in cushion protrusion between the castrated state, and proestrus and estrus, suggests that ovarian hormones exert an influence over the functional morphology of the cushions in a manner which promotes maximal uterine perfusion during those periods of the estrous cycle which are documented as periods of uterine hyperemia. These studies thus provide evidence for the dynamic role of intraarterial cushions in the regulation of uterine blood flow.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1092030103
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