3d. 2. The Uterine Tube
(Tuba Uterina [Fallopii]; Fallopian Tube; Oviduct)The uterine tubes (Figs. 1161, 1165) convey the ova from the ovaries to the cavity of the uterus. They are two in number, one on either side, situated in the upper margin of the broad ligament, and extending from the superior angle of the uterus to the side of the pelvis. Each tube is about 10 cm. long, and is described as consisting of three portions: (1) the isthmus, or medial constricted third; (2) the ampulla, or intermediate dilated portion, which curves over the ovary; and (3) the infundibulum with its abdominal ostium, surrounded by fimbriæ, one of which, the ovarian fimbria is attached to the ovary. The uterine tube is directed lateralward as far as the uterine pole of the ovary, and then ascends along the mesovarian border of the ovary to the tubal pole, over which it arches; finally it turns downward and ends in relation to the free border and medial surface of the ovary. The uterine opening is minute, and will only admit a fine bristle; the abdominal opening is somewhat larger. In connection with the fimbriæ of the uterine tube, or with the broad ligament close to them, there are frequently one or more small pedunculated vesicles. These are termed the appendices vesiculosæ (hydatids of Morgagni).
|Structure.The uterine tube consists of three coats: serous, muscular, and mucous. The external or serous coat is peritoneal. The middle or muscular coat consists of an external longitudinal and an internal circular layer of non-striped muscular fibers continuous with those of the uterus. The internal or mucous coat is continuous with the mucous lining of the uterus, and, at the abdominal ostium of the tube, with the peritoneum. It is thrown into longitudinal folds, which in the ampulla are much more extensive than in the isthmus. The lining epithelium is columnar and ciliated. This form of epithelium is also found on the inner surface of the fimbriæ. while on the outer or serous surfaces of these processes the epithelium gradually merges into the endothelium of the peritoneum.
|Fertilization of the ovum is believed (page 44) to occur in the tube, and the fertilized ovum is then normally passed on into the uterus; the ovum, however, may adhere to and undergo development in the uterine tube, giving rise to the commonest variety of ectopic gestation. In such cases the amnion and chorion are formed, but a true decidua is never present; and the gestation usually ends by extrusion of the ovum through the abdominal ostium, although it is not uncommon for the tube to rupture into the peritoneal cavity, this being accompanied by severe hemorrhage, and needing surgical interference.