Subserosa of uterine tube

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.