Portio vaginalis uteri
The portio vaginalis uteri ( lat. "Vaginal part of the uterus"), in clinical usage often referred to as portio (lat. "Part", "part"), is the part of the womb ( uterus ) that enters the vagina ( vagina ) protrudes. At the lower end of the cervix, the opening of the vaginalseitig preferred is the cervical canal as the outer cervix visible. The portion of the vagina surrounding the portio is called the vaginal vault ( fornix vaginae ). A portio vaginalis uteri occurs in most mammals ; it is absent in pigs , for example .
During the birth process, this narrow point in the woman's birth canal has to stretch to over ten centimeters. The midwife scans in the vaginal examination with two fingers the distance.
Physiological changes
The portio forms the boundary between the squamous epithelium of the vagina and the glandular epithelium of the cervical canal. This limit depends on the hormonal status of the woman. Both in the newborn girl and in the woman of childbearing potential, the glandular epithelium protrudes from the cervix and covers parts of the portio. In childhood or seniors , the portio is covered by squamous epithelium, the glandular epithelial cells recede into the cervical canal.
Conversion zone
In the case of a portioectopy , a so-called pseudo- erosion is formed by a protuberance of the cervical mucosa , in the area of which the non-keratinized squamous epithelium of the vagina transforms into the cylindrical epithelium of the cervix, forming stripe, cone or reticulate structures. The border between the squamous and columnar epithelium is also known as the transition zone.
As an open transition zone, the excretory ducts of the cervical glands open freely on the surface of the portio; as a closed transition zone , they are covered by squamous epithelium, so that retention cysts (so-called ovula nabothi ) can form.
histology
Changes in the squamous epithelium are known as cervical intraepithelial neoplasia (CIN). The histologically / microscopically visible change is referred to as the PAP status, but the classification is based on CIN.