FALLOPIAN TUBE OR OVIDUCT.
Tube uteri vel Fallopian, oriducti ; vasa spermatica vel ejaculantia, Lat. ; Ilfultertrom peten, Germ.; Trompes uterines, Trompes de Fallope, Fr.
The Fallopian tube (fig. 368. c c, and 404.. a b c) is the excretory duct of the ovary, as its homotype, the vas deferens, is the excretory conduit of the testis. And while in an anatomical point of view the tube is an appendage of the uterus, in a physio logical sense it must be regarded as the proper appurtenance of the ovary. But the Fallopian tube differs from the vas deferens, as well as from every other excretory duct in the animal economy, in this important particular, that it is entirely detached from its proper gland, between which and the uterus it serves to establish only a temporary communication.
This separation of the oviduct from the ovary is associated with a higher type Qf general structure than that which accompanies the blending of these parts. It is first ob served in the cartilaginous fishes, and prevails in all classes of the animal kingdom above them ; while in the osseous fishes and in the invertebrata possessing distinct ovaries, the oviducts are directly continuous with those bodies.
The Fallopian tube or oviduct is developed equally on both sides of the body in all vertebrate animals, except in the class Ayes, where the right tube becornes atrophied at an early period, while the left alone is de veloped.
In the human subject each ovary is pro vided with its proper oviduct, which serves to convey the ova from either side to the central organ, the uterus. But the detached position of the oviduct permits so great a range of motion in its free extremity, that, not only can this be applied to every part of the surface of the corresponding ovary, but the tube of one side may occasionally serve as a conduit to the opposite gland, and re ceive its product. The action of the tube, however, is then imperfect ; and, when im pregnation obtains, an abnormal form of ges tation usually results.
Form and dimensions.— Each oviduct has the form of a conical tube, the base of which is free and directed towards the ovary, while its apex is attached to the corresponding superior angle of the uterus, out of which it appears to arise.
The form of the tube was compared by Fallopius to that of a horn or trumpet, hich instrument, when straightened or only slightly curved, it sufficiently resembles. Issuing from the upper angle of the uterus, at the point of junction of the superior and lateral borders, the oviduct commences round and narrow (fig. 401. e), and proceeds outwardly gradually and regularly widening up to its dis tal extremity, where it contracts somewhat flexuosities, which produce an appearance of contraction at intervals. But that no such contractions really exist is rendered evident by suddenly just before terminating in a widely expanded funnel-shaped orifice. In the latter half of its course the tube exhibits certain distending the tube with air or water ; a pro cess which invariablyremoves this appearance, and serves to demonstrate the uniform and equable enlargement of the canal.
The length of the tube varies in different subjects, and to a slight extent on the two sides of the same subject. But this difference is not nearly so marked as that often ob served between the respective distances of the two ovaries from the uterus. The ordi nary range of length of the tube, measured between its extreme points and disregarding the flexuosities, is 3i--4i" ; but the curvature and flexuosities add usually 1—li" to this length.
The breadth of the tube is considerably greater at the distal than at the proximal encl. Just at the point of emergence from the uterine border, where the tube is firm and cord-like (fig. 404. e), its external diameter is li-2"'. From this point it gradually increases in breadth, and becomes softer, so as to assume the general appearance of an intestine. The mean diameter of the tube is found at about three-fifths of its length (b) from the uterine end, where it measures 2f" ; from this point the enlargement is more rapid, until the greatest diameter is attained just before the terminal contraction occurs, and here the transverse measurement is V'.