The lesions found in chronic salpingitis are numerous. The simplest form of the disease is the _chronic catarrhal salpingitis_, in which the pathological changes are confined to the mucous membrane of the tube. The muscular and peritoneal coats are not affected. The ostium abdominale remains open and is of the normal shape. The mucous membrane is congested. The folds of mucous membrane, or the plicæ, are hypertrophied from gradual infiltration of inflammatory products. The tube may become somewhat enlarged and more tortuous than normal. If the inflammatory condition extends to the middle or muscular coat of the tube, the _interstitial_ form of salpingitis is produced. The wall of the tube becomes thicker and harder. The microscope shows an increased amount of connective tissue in the tube-wall. As chronic salpingitis progresses the ciliæ of the lining cells disappear. If the disease extends through the peritoneal coat, inflammatory adhesions take place between the tube and neighboring structures. The tube is often found adherent to the posterior aspect of the uterus, the broad ligament, or the ovary. The most usual seat of adhesions is about the abdominal ostium. Adhesions here are caused by leakage or escape of septic material into the peritoneal cavity. The leakage is slow, and the gradually formed adhesions in time close the ostium by gluing it to adjacent structures, so that further escape of tubal contents by this opening is stopped. If, in such a case, the tube is freed from its adhesions, the fimbriæ will be found in the normal position with the ostium abdominale open. The usual method of closure of the distal end of the Fallopian tube is by another process. It takes place as follows: When the inflammation reaches the muscular coat of the tube, this coat becomes lengthened and extends beyond the fimbriæ, which apparently retract and become invaginated in the tube. The opening of the tube, instead of being flaring with protruding, diverging fimbriæ, becomes rounded and narrow (Fig. 147). The fimbriæ become drawn farther into the tube until they appear to be directed inward instead of outward. The ostium becomes narrower, and more rounded, until the edges finally meet and unite by peritoneal adhesions. Tubes representing all stages of this process of closure are often found in operating for inflammatory disease. Closure of the abdominal ostium by any method is to be viewed as a conservative process. It prevents leakage, through this channel, of septic material, and consequently diminishes the danger of peritonitis. [Illustration: FIG. 147.--Salpingitis with partial inversion of the fimbriæ.]