Medical assembly - having a medical tool (1; 14), - having a main body (2; 15) that has an access opening (3; 16) and a sleeve portion (5; 17) and is made of a unitary first plastics material, - having a closing body (7; 18) that closes the access opening (3; 16) and is made of a unitary second plastics material with a lower Shore hardness than the first plastics material, - wherein the tool (1; 14) is manufactured as a multicomponent injection-moulded part, - wherein the first and the second plastics material are coordinated with one another such that there is an adhesive bond between the main body (2; 15) and the closing body (7; 18), - wherein the second plastics material has piercing properties and is a thermoplastic elastomer, - having a connecting portion made of a third plastics material that has been pushed onto the sleeve portion of the main body and is connected thereto in an adhering and impermeable manner at its end via a connecting region, characterized in that - the first plastics material is coordinated with the third plastics material such that an adhesive bond between the main body and the connecting portion arises when they are heated to a temperature of less than 160°C, - the first plastics material is a mixture of polypropylene and a cycloolefin polymer, - a weight percentage ratio PP/COP is between 90:10 and 10:90, - the connecting portion comprises an acetate polymer or acrylate polymer. - having a medical tool (1; 14), - having a main body (2; 15) that has an access opening (3; 16) and a sleeve portion (5; 17) and is made of a unitary first plastics material, - having a closing body (7; 18) that closes the access opening (3; 16) and is made of a unitary second plastics material with a lower Shore hardness than the first plastics material, - wherein the tool (1; 14) is manufactured as a multicomponent injection-moulded part, - wherein the first and the second plastics material are coordinated with one another such that there is an adhesive bond between the main body (2; 15) and the closing body (7; 18), - wherein the second plastics material has piercing properties and is a thermoplastic elastomer, - having a main body (2; 15) that has an access opening (3; 16) and a sleeve portion (5; 17) and is made of a unitary first plastics material, - having a closing body (7; 18) that closes the access opening (3; 16) and is made of a unitary second plastics material with a lower Shore hardness than the first plastics material, - wherein the tool (1; 14) is manufactured as a multicomponent injection-moulded part, - wherein the first and the second plastics material are coordinated with one another such that there is an adhesive bond between the main body (2; 15) and the closing body (7; 18), - wherein the second plastics material has piercing properties and is a thermoplastic elastomer, - having a connecting portion made of a third plastics material that has been pushed onto the sleeve portion of the main body and is connected thereto in an adhering and impermeable manner at its end via a connecting region, characterized in that - the first plastics material is coordinated with the third plastics material such that an adhesive bond between the main body and the connecting portion arises when they are heated to a temperature of less than 160°C, - the first plastics material is a mixture of polypropylene and a cycloolefin polymer, - a weight percentage ratio PP/COP is between 90:10 and 10:90, - the connecting portion comprises an acetate polymer or acrylate polymer. - the first plastics material is coordinated with the third plastics material such that an adhesive bond between the main body and the connecting portion arises when they are heated to a temperature of less than 160°C, - the first plastics material is a mixture of polypropylene and a cycloolefin polymer, - a weight percentage ratio PP/COP is between 90:10 and 10:90, - the connecting portion comprises an acetate polymer or acrylate polymer.