A surgically implantable device is a single unit comprised of a hydraulically activated extendable cavernosal component and a manually controlled fluid transfer system composed of a pump. Flow from the pump is directed by a one way valve interposed between a bypass from an included elastic reservoir, the pump and a second one way valve interposed between the pump and the cavernosal unit. A manually controlled release valve, interposed between the outlet of the cavernosal unit and the reservoir, permits de-activation of the cavernosal unit and returns fluid to the reservoir. These components are housed by a molded tailpiece which stabilizes the device against the symphysis pubis, positions the cavernosal implant properly within the shaft of the penis and presents the controls for easy access. An access port permits adjustment of the fluid volume. The unit has utility as a tissue expander and penile re-construction in event of congenital or traumatic deformity.