A study of impression moulds of the genital tract of female fetuses.

Contrary to current opinion, the fetal vagina is not a solid plate. Already at the 14th week of gestation, the urethra, vagina, uterus, and Fallopian tubes have a lumen which can be identified by means of the intravaginal injection of rapidly setting silicon liquid. However, after the 26th week of gestation the injected substance fills the vagina but does not enter the cervical canal. This is probably due to functional plugging of the endocervical canal by the secretory activity of its epithelium. Silicon plastic moulds of the vaginal vault consistently show a circular groove separating the middle from thupper third of the vagina. This groove could be the line of fusion between the mesodermal Mullerian ducts and the urogenital sinus.