**2. Anatomy**

Each Fallopian tube is usually 10 cm long with variations in length from 7 to 14 cm. The abdominal ostium is situated at the base of a funnel-shaped expansion of the tube, the infundibulum. Medially, it opens into the thin-walled ampulla forming more than half the length of the tube and 1 or 2 cm in outer diameter; it is succeeded by the isthmus, a round and cord-like structure constituting the medial one-third of the tube and 0.5-1 cm in outer diameter. The isthmus continues through the uterine wall to the uterine cavity forming the interstitial or conual portion of the tube. This segment of the tube is about 1 cm in length and 1 mm in diameter.(Diamond, 1988)
