If the two rudiments of the uterus bipartitus are developed uniformly, according to the type of the one-horned uterus, two uterine halves are formed, which unite at one point of their convexity, and thus give rise to the uterus bicornis. The degree of this abnormity varies, and depends chiefly upon the point at which the two halves coalesce. The nearer the latter approaches to the external orifice, the more obtuse will be the angle at which the junction takes place, and consequently the more extensive the fissure. The higher the point of union, the more acute will be the angle, and it may thus become so small that the two halves lie almost parallel to one another, and there is only a slight divergence of the two horns. In the latter case the uterus closely resembles the normal condition; there is always a shallow excavation of the fundus between the projecting horns; the uterine cavity is either simple or divided by a septum of varying length.

The Part That Unites The Two Uterine Halves

The Part That Unites The Two Uterine Halves always represents the fundus uteri; the higher it is placed, the more this character becomes evident; and when it attains the same level as the uterine horns and surmounts them with its arch, the form of the two-horned uterus disappears. We consequently find, firstly, that the commissure in all cases occupies a horizontal position in the angle in which the two uterine halves meet.

Secondly

That the commissure is always developed in conformity with the fundamental type, viz. that it is a portion of uterine tissue presenting an arch posteriorly, or rather being obtuse-angled and thicker behind.

Thirdly

That when a septum exists it always proceeds from the commissure.

Fourthly

That, however low the commissure be placed, it exerts an evident influence upon the mutual position of the two uterine halves and the internal conformation of their cervices. This consists, in the first instance, in the slight convexity of the posterior, and the slight concavity of the anterior, surface of the uterus bicornis; and in the peculiar relation of the two uterine halves to one another, which is marked by a slight convergence and inclination anteriorly, thus affording the character of a normal uterus. The influence too that is exerted upon the pal-mae plicatae in the uterine halves is singular; the anterior one is placed internally next to the septum, the posterior one lies more externally, and on account of the greater thickness of the fundus uteri - corresponding to the normal character - more towards the posterior surface. The fact of the fundus being wedged in between the cervices in its original form, causes the palma plicata posterior to diverge still more; it induces a slight rotation of the uterine halves anteriorly, which is followed by the above-described form and position of the uterus bicornis.

The septum, which descends from the fundus uteri, may reach down to the os tincae and divide it, or it does not reach so far, and then the orifice or the cervix is common to both halves, or, lastly, it may be nearly or totally absent, and we then find the cavity of the cervix and the uterus more or less uniform, in proportion as the fundus itself is more or less elevated. If the latter is much depressed and presents no septum, a single cervical channel conducts into two uterine halves that diverge considerably, sometimes so far as to assume a horizontal position.

In rare cases, the two uterine halves do not coalesce, owing to coexisting malformations, such as fissures of the abdominal and pelvic parie-tes, of internal organs, especially the bladder and the intestine; the uterus thus remains completely divided, and the two halves are separated by the rectum, the colon, the small intestine, or by a rudimentary portion of either, by the mesentery, or the bladder. In the majority of cases, the inferior section of both, or at least of one uterine half, is but very imperfectly developed, and this applies still more to the vagina and to the pudenda.

The lowest degree of uterine fissure is represented by the bilocular uterus. Here the projection of the uterine horns has entirely disappeared; the fundus uteri occupies a position level with the orifices of the Fallopian tubes, and its convexity projects above them. The uterine cavity is divided into two vertical partitions by a central septum; the uterine horns present a normal divergence and the normal length. Yet even here the division of the uterine cavity is perceptible externally; the body of the uterus presenting greater breadth, and generally a shallow fundus, in consequence of which the uterus appears lower, and its dimensions do not, in most cases, exceed those of the normal uterus; the division is also indicated by a shallow furrow running down the posterior surface of the organ.