|External genital organs of female. The labia minora have been drawn apart.|
|Gray's||subject #270 1264|
Hymenal developmentThe genital tract develops during embryogenesis, from the third week of gestation to the second trimester, and the hymen is formed following the vagina.
At week seven, the urorectal septum forms and separates the rectum from the urogenital sinus.
At week nine, the müllerian ducts move downwards to reach the urogenital sinus, forming the uterovaginal canal and inserting into the urogenital sinus.
At week 12, the müllerian ducts fuse to create a primitive uterovaginal canal called unaleria
At month 5, the vaginal canalization is complete and the fetal hymen is formed from the proliferation of the sinovaginal bulbs (where müllerian ducts meet the urogenital sinus), and becomes perforate before or shortly after birth.
In newborn babies, still under the influence of the mother's hormones, the hymen is thick, pale pink, and redundant (folds in on itself and may protrude). For the first two to four years of life, the infant produces hormones that continue this effect. Their hymenal opening tends to be annular (circumferential).
Hymenal resorptionPast neonatal stage, the diameter of the hymenal opening (measured within the hymenal ring) has been proposed to be approximately 1 mm for each year of age. In children, to make this measurement, a doctor may place a Foley catheter into the vagina and inflate the balloon behind the hymen to stretch the hymenal margin and allow for a better examination. In the normal course of life, the hymenal opening can also be enlarged by tampon use, pelvic examinations with a speculum, regular physical activity (particularly horseback riding), or sexual intercourse. Once a girl reaches puberty, the hymen tends to become so elastic that it is not possible to determine whether a woman uses tampons or not by examining her hymen. In one survey, only 43% of women reported bleeding the first time they had intercourse, indicating that the hymens of a majority of women are sufficiently opened.
The hymen is most apparent in young girls: At this time, their hymen is thin and less likely to be redundant, that is to protrude or fold over on itself. In instances of suspected child abuse, doctors use the clock face system to describe the hymenal opening. The 12 o'clock position is below the urethra, and 6 o'clock is towards the anus, with the patient lying on her back.
Infants' hymenal openings tend to be redundant (sleeve-like, folding in on itself), and may be ring-shaped.
By the time a girl reaches school age, this hormonal influence has ceased, and the hymen becomes thin, smooth, delicate, and nearly translucent. It is also very sensitive to touch; a physician who must swab the area should avoid the hymen and swab the outer vulval vestibule instead.
Prepubescent girls' hymenal openings come in many shapes, depending on hormonal and activity level, the most common being crescentic (posterior rim): no tissue at the 12 o'clock position; crescent-shaped band of tissue from 1–2 to 10–11 o'clock, at its widest around 6 o'clock. From puberty onwards, depending on estrogen and activity levels, the hymenal tissue may be thicker, and the opening is often fimbriated or erratically shaped.
After giving birth, the vaginal opening usually has nothing left but hymenal tags (carunculae mytriformes) and is called "parous introitus".
Anatomic anomaliesagenesis or hypoplasia, canalization defects, lateral fusion and failure of resorption, resulting in various complications.
- Imperforate: hymenal opening nonexistent; will require minor surgery if it has not corrected itself by puberty to allow menstrual fluids to escape.
- Cribriform, or microperforate: sometimes confused for imperforate, the hymenal opening appears to be nonexistent, but has, under close examination, small openings.
- Septate: the hymenal opening has one or more bands extending across the opening.