Valved plug for endoscopic biopsy channel

A valved plug to be fitted on a mouth piece at an inlet opening of an instrument entrance passage leading to a biopsy channel of an endoscopic insertion tube, said plug being formed of a resilient material in its entirety and having, at opposite ends of a foldable connecting strip, a generally tubular main body portion internally formed with a constricted passage of a smaller diameter as compared with said inlet opening of said instrument entrance passage at an intermediate portion between outer and inner ends thereof, and a nesting piece adapted to be detachably and tightly coupled with said main body portion and having a normally closed slit valve in axial alignment with said constricted passage in said main body portion to permit insertion of an instrument therethrough, characterized in that:

• said main body portion is provided with an interlocking inward projection of a predetermined thickness at an outer end to be coupled with said nesting piece;
• and
• said nesting piece is composed of a circular body portion having a slit cut across a center region thereof, and an annular interlocking flange formed integrally with and on top of said circular body portion around said slit and spread radially outward to hang over circumferential edges of said circular body portion;
• said interlocking projection on said main body portion of said plug being adapted to be brought into engagement tightly with an interlocking groove formed between said flange portion and said circular body portion of said nesting piece and gripped in said interlocking groove in a compressed state when said nesting piece is coupled with said main body portion.