Vulva und vestibulum

The cervical canal is the spindle-shaped, flattened canal of the cervix , the neck of the uterus. It communicates with the uterine cavity via the internal orifice of the uterus or internal os and with the vagina via the external orifice of the uterus ostium of uterus or external os. The internal orifice of the uterus is an interior narrowing of the uterine cavity. It corresponds to a slight constriction known as the isthmus that can be seen on the surface of the uterus about midway between the apex and base. The external orifice of the uterus is a small, depressed, somewhat circular opening on the rounded extremity of the cervix , opening to the vagina.

Benign cystic lesions of the female external genitalia are frequently encountered in gynecologic and female urologic practices. True cystic lesions of the vagina and vulva originate from vaginal and vulvar tissues, respectively, but lesions arising from the urethra and surrounding tissues can appear as cystic lesions of the vagina and vulva as well. Most cysts of the female genitalia are located within the vagina, and their prevalence has been estimated to be 1 in women; however, this figure is probably an underestimation, because most cysts are asymptomatic and therefore not reported. Vaginal cysts typically occur in the third and fourth decades and are rarely found in prepubertal females except in countries where female circumcision in performed. Cysts of the vagina and vulva are usually asymptomatic, and their presence is usually noted as an incidental finding on physical examination. In patients whose cysts are discovered because of symptomatology, mild discomfort, patient detection of a mass, or urinary symptoms such as incontinence or obstructive voiding symptoms are common presenting symptoms.

Today it is generally held that the vagina develops from sinovaginal bulbs and that the lower third of the definitive vagina is derived from the urogenital sinus. We designed a genetic experiment in which the androgen receptor defect in the Tfm mouse was used to examine the effects of androgens. Vaginal development was studied by 3D reconstruction in androgen-treated female embryos and in complete androgen-insensitive littermates. In androgen-treated females, descent of the genital ducts was inhibited, and a vagina formed in androgen-insensitive Tfm embryos as it does in normal females.

The vulval vestibule or vulvar vestibule or vestibule of vagina is a part of the vulva between the labia minora into which the urinary meatus urethral opening and the vaginal opening open. Its edge is marked by Hart's line. It represents the distal end of the urogenital sinus of the embryo.