The length of the finibrim ranges from im to /". The principal leaflets, being con tinuations of the 4 — 6 main plicx of the tube, exceed the rest in size, and these, spreading like rays, form the more salient points of the fringes, while the intermediate spaces are filled up by the smaller appendages.
Intermixed with the latter are often seen minute pedunculated cysts, and especially little white hard grains, the size of millet seeds, first noticed by De Graaf. Similar grains are often observed upon the mesentery of the tube, or attached to the outer surface of the tube itself (fig. 404.).
The Tubo-ovarian lianzent and fringes. — This so-called ligament (fig. 408.) consists of one of the fimbrix, which is almost con stantly prolonged upon the outer margin or base of the triangular mesentery of the tube. Extending in the form of a slight furrow or channel ( fig. 404. d and fig. 405. e), be tween the outer extremity of the ovary and the inner or lower border of the tube, it is mar gined on either side by a row of leaflets, pos sessing shapes as variable as those which characterise the rest of the lesser fringes. These leaflets, as well as the furrow between them, are backed by a continuation of the peritoneal fold or mesentery, which, after enclosing the tube, here terminates abruptly on a level with its mouth, and thus is pro duced the appearance of a ligament, whose use is simply to preserve the tubal orifice in contiguity to the ovary; but there is no reason to think that it performs, as the an cient anatomists supposed, the office of a muscle in drawing these parts together.
The length of the tubo-ovarian ligament determines the distance to which the mouth of the tube can be separated from its corre sponding ovary. This, in most instances, is sufficient to permit the tubal orifice to be easily applied over any portion of the gland of the same side ; so that from whatever part of the surface of the ovary an ovum is discharged, the reception of the latter by the tube is rendered possible by the range of motion which the mouth of the tube enjoys in relation to the ovary. The average length of this ligament, measured from its com mencement at the margin of the ovary to the centre of the tubal orifice is li".
Structure of the coats or tunics.— The Fal lopian tube is composed of three coats : — viz., 1. an external investment of peritoneum; 2. a proper coat composed of fibrous tissue ; and 3. a mucous lining covered by epithe lium.
The tube has been already described as running horizontally within two folds of peritoneum, formed by the upper border of the lesser wing, or ala of the broad ligament, which serves also to form its rnesentery, and to connect it with adjacent parts. This fold encircles the tube somewhat loosely, and con stitutes the peritoneal coat.
Between this covering and the middle or pro per fibrous coat of the tube is found a small quantity of fine and rather tough connective tissue, which serves to bind these coats to gether. This intermediate tissue being more abundant in quantity towards the uterine end, permits a greater freedom of movement of the serous investment of the tube in this region than at the opposite or free extremity, where, in most subjects, the serous and pro per coats cannot be separated without much difficulty..
The middle or fibrous coat has been very generally regarded as containing muscular fibres, and as having a contractile power. Santorini described external, longitudinal, and internal circular fibres, and his state ment has been reasserted by Meckel, Boivin, Velpeau, and many others. By K011iker, also, the middle layer of this tube is regarded as a smooth muscular coat, composed of a double layer of fibres. These statements have been called in question by Robin and Richard, who assert that there are in the proper walls of the oviduct only fibres of cellular tissue and fibro-plastic elements, but no muscular fibres of organic life. AI. Ri chard declares that it is impossible to recog nise two distinct layers, at feast they can be only artificially produced. The number of longitudinal fasoculi appears always to ex ceed that of the transverse fibres, but these elements are interlaced in every direction, both longitudinally and transversely.