Uterus
The
uterus or
womb is the major female reproductive
organ of most
mammals, including
humans. One end, the
cervix, opens into the
vagina; the other is connected on both sides to the
fallopian tubes. In mammals, the four main forms in which it is found are: bipartite, as in cows; bicornuate, as in pigs; simplex, as with the
pear-shaped one found in humans and horses; and duplex, found in
rabbits.
The bilateral
Müllerian ducts form during early fetal life. In males,
MIF secreted from the testes leads to their regression. In females these ducts give rise to the
Fallopian tubes and the uterus. In humans the lower segments of the two ducts fuse to form a single uterus, however, in cases of
uterine malformations this development may be disturbed. The different uterine forms in various mammals are due to various degrees of fusion of the two Müllerian ducts.
The uterus is located inside the
pelvis immediately
dorsal (and usually somewhat
rostral) to the
urinary bladder and
ventral to the
rectum. It is held in place by eight
ligaments (one anterior; one posterior; two lateral or broad; two uterosacral; and two round ligaments).
* It is usually slightly "anteverted" (tipped forward) but is sometimes
retroverted (tipped backwards).
* Apart from the anteverted/retroverted distinction, the term "anteflexed" is sometimes used to indicate that the fundus is pointing forward relative to the cervix, or "retroflexed" when the fundus is pointing backwards. Under normal circumstances the uterus is both anteflexed and anteverted.
Outside of
pregnancy, its size is several
centimeters in diameter.
Ovary are also connected to uterus by two ligaments.
The uterus mostly consists of
muscle, known as myometrium. The innermost layer of myometrium is known as the
junctional zone, which becomes thickened in
adenomyosis. The lining of the uterine cavity is called the
endometrium. In most mammals, including humans, the endometrium builds a lining periodically which, if no pregnancy occurs, is shed or reabsorbed. Shedding of the endometrial lining in humans is responsible for
menstrual bleeding (known colloquially as a woman's "period") throughout the fertile years of a female and for some time beyond. In other mammals there may be cycles set as widely apart as six months or as frequently as a few days.
The loose surrounding tissue is called the
parametrium.
The main function of the uterus is to accept a fertilized
ovum which becomes implanted into the endometrium, and derives nourishment from blood vessels which develop exclusively for this purpose. The fertilized ovum becomes an
embryo, develops into a
fetus and gestates until
childbirth. Due to anatomical barriers such as the
pelvis, the uterus is pushed partially into the abdomen due to its expansion during pregnancy. Even in pregnancy the mass of a human uterus amounts to only about a kilogram (2.2 pounds).
Some
pathological states include:
*
Prolapse of the uterus
*
Carcinoma of the cervix - malignant neoplasm
*
Carcinoma of the uterus - malignant neoplasm
*
Ectopic pregnancy*
Fibroids - benign neoplasms
*
Adenomyosis - ectopic growth of endometrial tissue within the myometrium
*
Pyometra - infection of the uterus, most commonly seen in
dogs
The term
uterus is commonly used within the medical and related professions, whilst the term
womb is in more common usage.
*
WikiSaurus:womb — the
WikiSaurus list of synonyms and slang words for the womb in many languages
*
Myoma*
Myometrium* Egg (
ovum)
*
Ovary*
Menopause*
Vulva*
Vagina*
Penis*
Rokitansky syndrome*
Gray's*
Illustration
