Pelvic Anatomy Research Paper

Development

Pelvic anatomy including organs of the female reproductive system

The vaginal plate is a precursor to the inferior portion of the vagina; it is the growth of tissue that gives rise to the formation of the vagina, and is located where the solid tips of the paramesonephric ducts (Müllerian ducts) enter the dorsal wall of the urogenital sinus as the sinus tubercle. The plate's growth is unrestrained, as it significantly separates the cervix and the urogenital sinus; eventually, the central cells of the plate break down to form the vaginal lumen.[9] Until twenty to twenty-four weeks of pregnancy, the vagina is not fully formed as a canal. If it fails to fully develop, various septae can form, which may cause obstruction of the outflow

The vaginal mucosa is absent of glands. The vaginal epithelium consists of three rather arbitrary layers of cells[21] – superficial flat cells, intermediate cells and basal cells – and estrogen induces the intermediate and superficial cells to fill with glycogen. The superficial cells exfoliate continuously and basal cells replace them.[13][22][23] Under the influence of maternal estrogen, newborn females have a thick stratified squamous epithelium for two to four weeks after birth. After that, the epithelium remains thin with only a few layers of cells without glycogen until puberty, when the epithelium thickens and glycogen containing cells are formed again, under the influence of the girl's rising estrogen levels. Finally, the epithelium thins out during menopause onward and eventually ceases to contain glycogen, because of the lack of estrogen.[13][23][24] In abnormal circumstances, such as in pelvic organ prolapse, the vaginal epithelium may be exposed becoming dry and

It is closed by the labia minora in female virgins and in females who have never given birth (nulliparae), but may be exposed in females who have given birth (parous females).[13]

The hymen is a membrane of tissue that surrounds or partially covers the vaginal opening.[13] The effects of vaginal intercourse and childbirth on the hymen are variable. If the hymen is sufficiently elastic, it may return to nearly its original condition. In other cases, there may be remnants (carunculae myrtiformes), or it may appear completely absent after repeated penetration.[26] Additionally, the hymen may be lacerated by disease, injury, medical examination, masturbation or physical exercise. For these reasons, it is not possible to definitively determine whether or not a girl or woman is a virgin by examining her