A connecting structure for connecting a first member in fluid flow connection with a second member may include a receptacle structure provided on the first member and having an interior chamber and an opening into the interior chamber in which a needle and a pierceable member surrounding a piercing end of the needle may be supported. The second member may include a connection portion that has a septum supported in an interior chamber having a size and shape suitable to be received at least partially into the opening of the receptacle structure upon moving the first member and the second member together to push the pierceable member toward the piercing end of the needle to cause the piercing end of the needle to pierce the pierceable member and the septum to come into fluid flow communication with the interior chamber of the connection portion.