Tissue expander with protection against accidental puncture

This invention relates to implantable tissue expanders and prostheses, and more particularly to implantable mammary soft tissue expanders and prostheses. The mammary prostheses of the invention have a self-sealing area in the upper pole region of the anterior face. The self-sealing area is greater than that of a traditional filling port, and reduces the severity of the consequences of an inadvertent puncture by a hypodermic needle during the filling process. Also, this self-sealing area is thicker than the material in the other areas of the prosthesis, causing fluid introduced to the prosthesis to stay in the lower pole region of the prosthesis, making the shape of the prosthesis appear more like that of a natural breast.