Abstract: A seal 10 comprises a bushing 11 and a thread 12, wherein the bushing 11 has a first lumen 15 and a second lumen 16. The lumina 15 and 16 extend along the entire length of the bushing 11. The thread 12 can be introduced at one end into the second lumen 16 and has a swelling 21 at the free end which prevents reintroduction and travel of the end of the thread through the second lumen 16. The thread 12 can be introduced into the first lumen 15 via its other free end and pushed through first lumen 15. Enlargements 20 are formed on the thread 12 having a size preventing introduction into the first lumen 15 without the exercise of force. The bushing 11 and the thread 12 are manufactured from a flexible material having a stable shape. When the enlargements 20 are pulled into the first lumen 15, the bushing 11 bends and seats on e.g. tissue to be ligated. When the enlargements 20 are completely pulled into the first lumen 15, the seal 10 is permanently closed.