The Pavilion, or Infinulibulunt consists of the expanded or trumpet-mouthed portion of the tube which lies between the orifice just described and the fringed margin in which the tube-walls actually terminate. No por tion of the Fallopian tube is so variable in form and construction as this, and yet none is of such importance, for upon the peculiar construction of this part depends the special action of the oviduct in grasping the surface of the ovary, and receiving and conveying away, the ovum.
The representations which in illustrated works usually accompany the description of this part serve to give but a feeble notion of the beauty of its construction, apparently, be cause the advice of De Graaf, that their structure should be examined under water, has been commonly neglected. But without the support derived from a fluid of greater density than the atinosphere, the extremely delicate plicm and fringes with which the ex panded mouthpiece of the tube is beset, col lapse and exhibit nothing more than a ge neral indication or outline of their true form.
When thus examined, the pas ilion in young and healthy subjects is observed to be funnel-shaped, and to have arranged upon its inner surface numerous folds and leaflets, which are merely continuations of the larger and smaller plic lining the cavity of the tube. These folds, which are irregu larly though often very closely set, con ver,,e towards the centre of the orifice of the tube, and in some cases appear by their pro fusion almost to block up the entrance of the canal. The office of these folds is doubtless to receive and entangle the delicate ovum in one of the numerous channels which are formed between the sets of leaflets, and so to conduct it infallibly, into the common orifice towards mhich they all converge.
So great is the variety perceptible in the conformation of this structure in different sub jects, that it would be difficult to find any two in which a precisely similar arrangement of parts obtained. Even in the same body there is often a material difference in the pavilion of the two sides. And these varieties are not attributable to mere individual pecu liarities of form, but they appear to bear a certain relation to the age of the person in whom they are found*, and consequently to the period of functional activity or other wise of the structures of which they form an importart part. Thus in young subjects, after the ar,e of puberty, and in those who have bornebfew children, the pavilion exhibits that richness and profusion of folds and fringes which is represented in figs. 404. and 419. while in multiparm and those advanced in life a greater simplicity of form in this part is commonly observed ; but between these extremes every variety of arrangement mav be observed.
in the fcetus, and in very young subjects, the margin of the pavilion is nearly evenly circular. This form is also seen in adults in those rare cases where the prolongation of one of the fimbrive along the tubo-ovarian ligament does not occur, but commonly the margin is uneven or scolloped, as shown in fig. 407.
At this point, the opportunity occurs of examining an arrange ment of parts %ihich is unique in the animal economy, viz., the junction of a serous with a mucous brane. The line of junction of these two • Richard, These, Anatomic des Trompes de l'Ut6rus chez la Femme. 1851.
surfaces may here be traced along the mar gin where the tube wall terminates. Here the peritoneal or outer covering of the tube may be observed to cease suddenly in the form of a distinct boundary line, as in the example represented in fig. 407. But oc casionally the peritoneal coat is prolonged upon the base of the principal leaflets which crest the end of the canal, and in that case a closer examination is necessary in order to discover the line of union between the mu cous and the serous surfaces.
The fi»zbrice, lacinice (AaKis), or morsus dia boli. —The structure and composition of these appendages differ in no respect from those of the pliem or folds of which they are merely continuations. These fimbrim present many varieties of form, but are generally either pe tiolate, lanceolate, or simply filiform. Their margins are in some cases coarsely crenate, like those of the tubal plicw, while in other instances they are so finely indented, as to require the use of a lens for their examina tion. The greater number of these fimbrim are attached to the sides or margins of the infundibulum by their narrower extremity only, like leaves thickly clustered on the branches of a tree, while the more obtuse ex tremity of each leaflet is left free, apparently with the object of increasing the extent of surface of the tube-mouth, vvhich may be applied to the superficies of the ovary. But very commonly one or two fimbri are ob served to be firmly attached by both ends, while the body extends horizontally in the form of a flattened band among the rest of the fringes, as at fig. 408. d. The backs of these are always covered by a continuation of the serous membrane. It is difficult to imagine a use for them unless they are placed there as a safeguard to diminish the risk of a retrograde movement and escape of the ovum after it has entered the tube along one of the furrows formed between the phew.