Abstract: A tissue expander capable of insertion in a human body to induce formation of a pocket into which a mammary prosthesis may be inserted including an expander portion which is flaccid and is adapted to be inflated progressively in the body to induce formation of said pocket, a support plate portion which is sufficiently flexible that it may be bent or folded upon itself for insertion into or removal from the body through an incision in the body and to recover to a plate-like condition within the body, feed tube and releasable fastener preferably a snap fastener whereby the support portion and the expander portion are connected together until it is desired to release the expander portion from the support portion.