In the outer portion of the tube the mucous membrane is thrown into longitudinal folds or plicæ. These folds increase in thickness and in number as the ostium abdominale is approached. The difference in the degree of plication at the two ends of the tube is shown by Figs. 142, 143. The folds of mucous membrane project beyond the ostium to form the fimbriæ. Like the rest of the mucous membrane, the fimbriæ are covered by columnar ciliated epithelium. The peritoneal covering does not, as a rule, extend on to the fimbriæ. It terminates by a sharp line which marks also the termination of the circular muscular fibers of the middle coat of the tube. The fimbriæ are subject to great variation in number and in distribution. Sometimes the Fallopian tube has one or two accessory ostia in the vicinity of the usual opening. These accessory ostia are situated on the upper aspect of the tube and are surrounded by more or less luxuriant fimbriæ. Occasionally a small pedunculated tuft of fimbriæ is found on the outer portion of the tube (Fig. 144, _B_). In some cases there is an accessory tubal end supplied with an ostium (Fig. 144, _A_). [Illustration: FIG. 143.--Section of the normal Fallopian tube near the abdominal ostium (Beyea).] [Illustration: FIG. 144.--Fallopian tube and ovary: _A_, accessory tubal end with an ostium; _B_, pedunculated tuft of fimbriæ.] [Illustration: FIG. 145.--Fallopian tube, ovary, and parovarium: _a_, hydatid of Morgagni; _b_, cyst of Kobelt’s tube; _c_, Gärtner’s duct.] Very often a small pedunculated cyst, about the size of a pea, is found attached to the fimbriæ or to the outer aspect of the tube. These cysts are called hydatids, or cysts of Morgagni. They are said to occur in about 8 per cent. of adults and in 20 per cent. of fetuses. They are not pathological. The cyst wall is composed of three coats: an external peritoneal coat; a middle muscular coat, arranged in two layers; and an inner mucous coat covered with columnar ciliated epithelium. The cyst contains a clear watery fluid. No distinct glands, such as are found in the cervix and the body of the uterus, have been observed in the Fallopian tubes. The mucous crypts formed by the folds of the mucous membrane are probably glandular in character and secrete an albuminous fluid. INFLAMMATION OF THE FALLOPIAN TUBES, OR SALPINGITIS. Inflammation is the disease that most usually affects the Fallopian tubes. The condition is, as a rule, secondary to endometritis, the mucous membrane of the tubes becoming inflamed by direct extension from the mucous membrane of the uterus. The causes of salpingitis are as numerous as those of endometritis. The most common causes of salpingitis are sepsis and gonorrhea. Any form of inflammation of the endometrium may extend to the Fallopian tubes, but the septic and the gonorrheal forms of endometritis are especially virulent, and it is the rule in these diseases that the tubes are affected.