Hymen

Hymen
External genital organs of female. The labia minora have been drawn apart.
Latin	hymen vaginae
Gray's	subject #270 1264
MeSH	Hymen

The Hymen is a membrane that surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia.^[1][2][3] The size of the hymenal opening increases with age. It is not possible to confirm with certainty that a woman is a virgin by examining her hymen.^[2][3] In cases of suspected rape or sexual abuse, a detailed examination of the hymen may be performed; but the condition of the hymen alone is often inconclusive. In younger children a torn hymen will typically heal very fast, in adolescents the hymenal opening does extend from natural causes and variation in shape and appearance increases.^[1] In children, although a common appearance of the hymen is crescent-shaped, many variations are possible.^[1] After a woman gives birth, she may be left with remnants of the hymen, called carunculae myrtiformes, or the hymen may be completely absent.^[4]

Contents 1 Hymenal development 2 Hymenal resorption 3 Anatomic anomalies 4 Hymens in other animals 5 Hymenorrhaphy 6 Womb fury

Hymenal development

The 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.^[5] Their hymenal opening tends to be annular (circumferential).^[6]

Hymenal resorption

Past 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.^[7] 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.^[1] 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.^[1][5]
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.^[8] 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.^[9]
Infants' hymenal openings tend to be redundant (sleeve-like, folding in on itself), and may be ring-shaped.^[9]
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.^[5]
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.^[6]
After giving birth, the vaginal opening usually has nothing left but hymenal tags (carunculae mytriformes) and is called "parous introitus".

Anatomic anomalies

Various types of hymen

Anomalies of the female reproductive tract can result from agenesis or hypoplasia, canalization defects, lateral fusion and failure of resorption, resulting in various complications.^[7]

• Imperforate:^[10][11] 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.

Hymens in other animals

Due to similar reproductive system development, many mammals, including chimpanzees, elephants, manatees, whales, and horses, retain hymens.^[12][13]

Hymenorrhaphy

Main article: Hymenorrhaphy

In some cultures, an intact hymen is highly valued at marriage.^[14][15][16] Some women undergo hymenoplasty, a restoration of their hymen.^[16][17]

Womb fury

In the sixteenth and seventeenth centuries, medical researchers used the presence of the hymen, or lack thereof, as founding evidence of physical diseases such as "womb-fury" (Hysteria). If not cured, womb-fury would, according to these early doctors, result in death.^[18][19]