11. Then, the strand zips through a narrow tube . 12. Construction of a narrow tube lined with mucosa ( a urethra ) is a similar challenge. 13. When the narrow tube opened up, we were once again standing upright in a large chamber. 14. Radiologist Graham Lee uses narrow tubes called catheters to inject a clot-buster called urokinase directly into clots. 15. The new form also consists of narrow tubes , but the tubes are connected in a willowy lattice. 16. This gave a more vertical arrangement of the water-tubes, thus encouraging thermosyphon circulation in these narrow tubes . 17. A narrow tube will sound " reedy ", while a wide one will sound " flutey ". 18. The narrow tube is then removed. 19. A long, narrow tube called a catheter is inserted through a plastic hollow tube called an introducer sheath. 20. Catheters are narrow tubes that doctors snake through the circulatory system to approach blockages from inside a blood vessel.
