Endoscopic image of the human foetus in vivo, after 9 weeks, showing: the stomach (bottom, left), the coiled intestines (centre, right), and the umbilicus (top), which carries 2 arteries that remove deoxygenated blood and a vein that provides oxygenated blood for the foetus. The endoscope, a series of lenses and a fibre- optic light guide, is inserted through the cervix and manipulated until a "window" into the amniotic sac is found (ie an area where the wall is thinner).