An intrauterine system for the retention of a biologically active compound within the uterus of a female mammal is formed by a frame defining an interior space for receipt of a deposit of the compound. The frame has an open structure allowing access to a substantial part of an outer surface of the deposit and the deposit has a rate controlling structure that controls a rate of release of the compound within the uterus. Retention elements are provided on the frame for retaining the frame within the uterus.一種用於滯留生物活性化合物於雌性哺乳類之子宮內的子宮內系統係由框架組成，該框架定義接受該化合物之沈積物之內部空間。該框架具有允許取用該沈積物外部表面之實質部份的開放構造，且該沈積物具有可控制該化合物在子宮內之釋放速率的速率控制構造。留置元件係設置於該框架上以將該框架留置於子宮內。
