An injection device having a first sub-assembly (110) comprises a housing (111) and a chamber (112). The chamber is disposed within the housing and has proximal and distal ends, an inner surface and an exit aperture (114). The sub-assembly comprises a stopper (113) movably disposed within the chamber. The stopper has an outer surface substantially in contact with the inner surface about its perimeter. The sub-assembly comprises a port (118) adapted to receive a container (1199) containing a fluid. The stopper is fixed with respect to the housing and movement of the port causes movement of the exit aperture in relation to the stopper.
