The present invention includes a base member (2), a container for an inner vessel interior (28) and a container adapted to receive a material comprising a container closure (23) for sealing the fluid-tight (20), the container a medical device comprising a fluid connection means (50) and for establishing a fluid connection to the interior. Cover receiving portion (36) for removably mounted is covered (4), the cover (4) and fluid connection means (50) in response to relative movement between the base member (2) and the container closure (23 ) and it is operably coupled to the fluid connection means (50) to cause the relative motion between. Medical devices, preventing the removal movement of the cover relative to the cover receiving part when there is the cover and the base member in a first relative position in which the fluid connection means (50) and the container interior (28) is fluidly isolated as well as to permit removal movement of the cover (4) against the cover receiving portion when there is a cover and a base member in a second relative position in which the inner fluid connection means and the vessel is fluidly connected (36) Furthermore it comprises a cover engaging mechanism (9,37,46,49) configured to.本発明は、ベース部材(2)と、物質を受け入れるようになっている容器内部(28)および容器内部を流体密にシールするための容器閉塞体(23)を備える容器(20)と、容器内部に対する流体接続を確立するための流体接続手段(50)とを備える医療機器に関する。カバー受け部(36)に取り外し可能に装着されるカバー(4)は、カバー(4)とベース部材(2)との間の相対動作に応じて流体接続手段(50)と容器閉塞体(23)との間の相対動作を引き起こすために流体接続手段(50)と作用可能に結合される。医療機器は、流体接続手段(50)と容器内部(28)とが流体的に分離される第1の相対位置にカバーおよびベース部材があるときにカバー受け部に対するカバーの取り外し方向の動きを防止するとともに、流体接続手段と容器内部とが流体的に接続される第2の相対位置にカバーおよびベース部材があるときにカバー受け部(36)に対するカバー(4)の取り外し方向の動きを許容するように構成されるカバー係合機構(9,37,46,49)を更に備える。