In the absence of testosterone during sexual differentiation (sex development of the differences between males and females), the urogenital sinus persists as the vestibule of the vagina, the two urogenital folds (elongated spindle-shaped structures that contribute to the formation of the urethral groove on the belly aspect of the genital tubercle) form the labia minora, and the labioscrotal swellings enlarge to form the labia majora.
Vagina develops into an elastic muscular canal that extends from the vulva to the uterus. It is reddish pink in color, and it connects the superficial vulva to the cervix of the deep uterus. The vagina is posterior to the urethra and bladder, and reaches across the perineum superiorly and posteriorly toward the cervix; at approximately a 90 degree angle, the cervix protrudes into the vagina. The vaginal orifice and urethral opening are protected by the labia.
Anatomical structure
The vagina is situated between the cervix of the uterus and the external genitalia, primarily the vulva (Pic.1). Although there is wide anatomical variation, the length of the unaroused vagina of a woman of child-bearing age is approximately 6 to 7.5 cm (2.5 to 3 in) across the anterior wall (front) and 9 cm (3.5 in) long across the posterior wall (rear).
During sexual arousal, the vagina expands in both length and width. If a woman stands upright, the vaginal tube points in an upward-backward direction and forms an angle of approximately 45 degrees with the uterus and of about 60 degrees to the horizontal. The vaginal opening and hymen also vary in size; in children, although a common appearance of the hymen is crescent-shaped, many shapes are possible (Pic.2).
The vaginal opening is at the caudal end of the vulva, behind the opening of the urethra. The upper one-fourth of the vagina is separated from the rectum by the recto-uterine pouch. Above the vagina is the mons pubis. The vagina, along with the inside of the vulva, is reddish pink in color. A series of ridges produced by the folding of the wall of the outer third of the vagina is called the vaginal rugae (Pic.3). They are transverse epithelial ridges and they provide the vagina with increased surface area for extension and stretching.
The hymen is a membrane of tissue that surrounds or partially covers the external vaginal opening. The tissue may or may not be ruptured by vaginal penetration. It can also be ruptured by delivery, a pelvic examination, injury, or sports. The absence of a hymen may not indicate prior sexual activity. Similarly, its presence may not indicate a lack of prior sexual activity.
Supporting the vagina are its upper third, middle third and lower third muscles and ligaments.The upper third are the levator ani muscles:
The middle third of the vagina concerns the urogenital diaphragm (also described as the paracolpos and pelvic diaphragm). The lower third is the perineal body; it may be described as containing the perineal body, pelvic diaphragm and urogenital diaphragm.
Histological structure
The wall of the vagina from the lumen outwards consists of:
Some texts list four layers by counting the two sublayers of the mucosa (epithelium and lamina propria) separately. The lamina propria is rich in blood vessels and lymphatic channels. The muscular layer is composed of smooth muscle fibers, with an outer layer of longitudinal muscle, an inner layer of circular muscle, and oblique muscle fibers between. The outer layer, the adventitia, is a thin dense layer of connective tissue, and it blends with loose connective tissue containing blood vessels, lymphatic vessels and nerve fibers that is present between the pelvic organs.
The mucosa forms folds or rugae (Pic.5), which are more prominent in the caudal third of the vagina; they appear as transverse ridges and their function is to provide the vagina with increased surface area for extension and stretching.
Where the vaginal lumen surrounds the cervix of the uterus, it is divided into four continuous regions or vaginal fornices:
The posterior fornix is deeper than the anterior fornix. While the anterior and posterior walls are placed together, the lateral walls, especially their middle area, are relatively more rigid; because of this, they vagina has a H-shaped cross section. Behind, the upper one-fourth of the vagina is separated from the rectum by the recto-uterine pouch. Superficially, in front of the pubic bone, a cushion of fat called the mons pubis forms the uppermost part of the vulva.
The epithelial covering of the cervix is continuous with the epithelial lining of the vagina. The vaginal mucosa is absent of glands. The vaginal epithelium consists of three rather arbitrary layers of cells:
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. In abnormal circumstances, such as in pelvic organ prolapse, the vaginal epithelium may be exposed becoming dry and keratinized.
Inborn morphological deviation of the uterus - one of the Müllerian duct anomalies where the uterine cavity is divided in the upper part.
Cancer that arises from the endometrium, the lining of the uterus.
A distally blocked Fallopian tube filled with pus.
A type of female genital malformation resulting from an abnormal development of the Müllerian duct(s) during embryogenesis.
Congenital uterine malformation where both Müllerian ducts develop but fail to fuse, thus the woman has a "double uterus".
A form of a congenital malformation where the uterine cavity is partitioned by a longitudinal septum. It is one of Müllerian duct anomalies.
A physical or psychological condition in which woman cannot engage in any form of vaginal penetration.
Glands that produce a thick mucus that maintains moisture in the vulva area.
The uterus is the largest and major organ of the female reproductive tract that is the site of fetal growth and is hormonally responsive
A medical condition whose main symptom is low sexual desire.
The need to urinate more often than usual and a sudden, compelling urge to urinate.
Short or scanty periods with extremely light menstrual blood flow.
A condition that affects a woman's ability to engage in vaginal penetration.
The failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse.
The medical term for infrequent, often light menstrual periods (intervals exceeding 35 days).
The absence of sexual appetite.
The painful feelings during sexual intercourse.
A burning or stinging sensation during urination.
The medical term for cycles with intervals of 21 days or fewer.
A combination of physical and emotional disturbances that occur after a woman ovulates and ends with menstruation.
A frustration caused by a discrepancy between a person's desired and achieved sexual activity.
The biological fluid secreted from the vagina.
Decreased or missing lubrication of vagina.
