| 摘要 |
<p>A sphincter valve has a membrane formed with at least one slit defined by petals, which membrane adopts a convex dished configuration when the valve is closed and inverts into a concave configuration when the valve is opened. In the invention, an abutment member is movable relative to the membrane for opening the valve by making direct contact with the petals to open the slit between the petals.</p> |
