| 摘要 |
An elongated, rigid cannula has a peripheral wall defining a central bore and a side port for introduction of material into the bore. A covering of resilient, flexible material is provided in the area of the side port, with a corresponding aperture aligned with the port of the cannula. The aperture of the resilient covering can be somewhat smaller than the underlying cannula port, forming a resilient margin that overhangs and surrounds the port.
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