A division of the duct into uterus or cornii, and narrower Fallopian tube, is still nowhere perceptible, and the place of this latter divi sion is only as yet indicated by the addition of the substance NA hich afterwards becomes ligamentum rotundum. Between the oviduct and the ovary lies the atrophied Wolffian body of a dirty yellow colour, in part surrounding the ovary ; but notwithstanding this conti guity the tubuli of the Wolffian body form no union between the Fallopian tube and the ovary. The duct, or future Fallopian tube, which had previously preserved a perpendi cular direction, now takes, with the rest of these parts, a more sunken position. But it still lies close to the Wolffian body, from which it is separated by a narrow fold of peritoneum.
In older female embryos the Fallopian tubes, now more completely formed, are thicker and exhibit a somewhat undulating outline. The Wolffian bodies, much reduced in size, may be found lying in a duplicature of peritoneum, between the ovaries and the oviducts. The inferior portion of the latter becomes wi dened, and the division between the tubes and the horns, or cornua, of the uterus is established ; although the tube still remains relatively very broad, even up to its abdomi nal end.
In the human subject the opportunities for observation upon very early embryos being of not very frequent occurrence, the foregoing changes have not been so accurately traced in the first stages as in the embryos of birds and mammals ; but all the examina tions which have yet been made lead to the conclusion that the Fallopian tube has its origin in a duct similar to that already described. This, with the rest of the in
ternal organs, is sufficiently developed by the third month of utero-gestation to leave no longer any doubt as to the sex. By this period the oviducts have nearly acquired that horizontal position which, from the fourth month onwards, becomes a more marked cha racteristic. In embryos of the fourth month the tubes run parallel with the now horizon tally placed ovaries, whose elongated form corresponds with the tube in the greater por tion of its length. By the end of' this month the abdominal end of the tube is seen to be wide open, and traces of the fimbrim are dis coverable in its already fringed margin. The lower ends of the tubes are still not so com pletely united but that an indentation is per ceptible at their point of junction, giving evidence of the still bi-corned condition of the uterus. From this period onwards the proper structure of the tube wall appears to grow with greater rapidity than the fold of peritoneum by which it is invested ; so that in advanced embryos, and in the fcetus at term, the ovi duct is usually found of a tortuous or serpentine form, its windings being easily dis tinguishable through the peritoneal sheath. The tube now much exceeds the ovary in length, and its infundibulur end is beautifully margined with delicate fimbrim (fig. 418.).