The muscular coat consists of unstriped muscular fiber which is continuous with that of the uterus. The muscular fibers are arranged in two layers, an outer longitudinal and an inner circular layer.
The inner or mucous coat, which is continuous with the mucous membrane of the uterus, is covered with columnar ciliated epithelium.
Fig. 142.—Section of the normal Fallopian tube near the uterine cornu (Beyea).
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).
Fig. 143.—Section of the normal Fallopian tube near the abdominal ostium (Beyea).
Fig. 144.—Fallopian tube and ovary: A, accessory tubal end with an ostium; B, pedunculated tuft of fimbriæ.