A connection system for connecting an inside environment of a compartment to an environment outside said compartment, said compartment being isolated relative to the outside environment and the connection system comprising: a connecting wall to separate said inside environment from said outside environment, said connecting wall having a communication orifice arranged to receive a through connecting element having a main body on which a case is removably mounted, and an innner removable closing device inside said compartment arranged to tightly seal said communication orifice of said compartment, arranged to be able to be coupled separately with said case mounted on said main body of said connecting element and arranged such that, when it is removed from the inside of the compartment, it allows a simultaneous removal of said case by separating it from said main body of said connecting element, said connection system further comprising a blocking device, said blocking device comprising, at said connecting wall on the outside environment side, a control element (5, 5') for controlling a blocking mechanism, said control element (5, 5') having - a first open position to allow said connecting element to be inserted into said communication orifice and into said inner removable closing device and to control said blocking mechanism so that it blocks any movement by said inner removable blocking device, and - a second closing position to block said connecting element received in said communication orifice at said connecting wall on the outer side and to allow said blocking mechanism to authorize a movement of said inner removable closing device, said blocking mechanism being arranged to - block said control element (5, 5') in the closed position once a movement has been initiated to remove said inner removable closing device, and - maintain said blocking movement of said control element (5, 5') in the closed position during a continuation of said movement to remove said inner removable closing device, up to and including its complete removal. a connecting wall to separate said inside environment from said outside environment, said connecting wall having a communication orifice arranged to receive a through connecting element having a main body on which a case is removably mounted, and an innner removable closing device inside said compartment arranged to tightly seal said communication orifice of said compartment, arranged to be able to be coupled separately with said case mounted on said main body of said connecting element and arranged such that, when it is removed from the inside of the compartment, it allows a simultaneous removal of said case by separating it from said main body of said connecting element, said connection system further comprising a blocking device, said blocking device comprising, at said connecting wall on the outside environment side, a control element (5, 5') for controlling a blocking mechanism, said control element (5, 5') having - a first open position to allow said connecting element to be inserted into said communication orifice and into said inner removable closing device and to control said blocking mechanism so that it blocks any movement by said inner removable blocking device, and - a second closing position to block said connecting element received in said communication orifice at said connecting wall on the outer side and to allow said blocking mechanism to authorize a movement of said inner removable closing device, said blocking mechanism being arranged to - block said control element (5, 5') in the closed position once a movement has been initiated to remove said inner removable closing device, and - maintain said blocking movement of said control element (5, 5') in the closed position during a continuation of said movement to remove said inner removable closing device, up to and including its complete removal. - a first open position to allow said connecting element to be inserted into said communication orifice and into said inner removable closing device and to control said blocking mechanism so that it blocks any movement by said inner removable blocking device, and - a second closing position to block said connecting element received in said communication orifice at said connecting wall on the outer side and to allow said blocking mechanism to authorize a movement of said inner removable closing device, - block said control element (5, 5') in the closed position once a movement has been initiated to remove said inner removable closing device, and - maintain said blocking movement of said control element (5, 5') in the closed position during a continuation of said movement to remove said inner removable closing device, up to and including its complete removal.