The reproductive function of the uterus is to accept a fertilized ovum which passes through the utero-tubal junction from the fallopian tube. It implants into the endometrium, and derives nourishment from blood vessels which develop exclusively for this purpose.
The fertilized ovum becomes an embryo, attaches to a wall of the uterus, creates a placenta, and develops into a fetus (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 during pregnancy the mass of a human uterus amounts to only about a kilogram (2.2 pounds).
The uterus is essential in sexual response by directing blood flow to the pelvis and to the external genitalia, including the ovaries, vagina, labia, and clitoris.
The series of changes in which the uterine lining is shed, rebuilds, and
prepares for implantation.The timing of the menstrual cycle starts with the first day of menses, referred to as day one of a woman’s period. Cycle length is determined by counting the days between the onset of bleeding in two subsequent cycles. Because the average length of a woman’s menstrual cycle is 28 days, this is the time period used to identify the timing of events in the cycle. However, the length of the menstrual cycle varies among women, and even in the same woman from one cycle to the next,typically from 21 to 32 days.
Just as the hormones produced by the granulosa and theca cells of the ovary “drive” the follicular and luteal phases of the ovarian cycle, they also control the three distinct phases of the menstrual cycle. These are the menses phase, the proliferative phase, and the secretory phase.
Bilateral Müllerian ducts form during early fetal life. 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 (Pic. 1). The human uterus is pear-shaped and about three inches (7.6 cm) long. A nonpregnant adult uterus weighs about 60 grams. The uterus can be divided anatomically into four segments:
The uterus consists of a body and a cervix (Pic. 2). The cervix protrudes into the vagina. The uterus is held in position within the pelvis by condensations of endopelvic fascia, which are called ligaments. These ligaments include the:
It is covered by a sheet-like fold of peritoneum, the broad ligament.
The endometrium (Pic. 3) consists of a single layer of columnar epithelium plus the stroma on which it rests. The stroma is a layer of connective tissue that varies in thickness according to hormonal influences. Simple tubular uterine glands reach from the endometrial surface through to the base of the stroma, which also carries a rich blood supply of spiral arteries. In a woman of reproductive age, two layers of endometrium can be distinguished. These two layers occur only in endometrium lining the cavity of the uterus, not in the lining of the uterine (Fallopian) tubes.
The functional layer is adjacent to the uterine cavity. This layer is built up after the end of menstruation during the first part of the previous menstrual cycle. Proliferation is induced by estrogen (follicular phase of menstrual cycle), and later changes in this layer are engendered by progesterone from the corpus luteum (luteal phase). It is adapted to provide an optimum environment for the implantation and growth of the embryo. This layer is completely shed during menstruation.
The basal layer, adjacent to the myometrium and below the functional layer, is not shed at any time during the menstrual cycle, and from it the functional layer develops.
In the absence of progesterone, the arteries supplying blood to the functional layer constrict, so that cells in that layer become ischaemic and die, leading to menstruation.
The myometrium (Pic. 4), is located between the endometrium (the inner layer of the uterine wall), and the serosa or perimetrium (the outer uterine layer).
Myometrium has 3 layers:
The inner one-third of the myometrium (termed the junctional or sub-endometrial layer) appears to be derived from the Müllerian duct, while the outer, more predominant layer myometrium appears to originate from non-Mullerian tissue, and is the major contractile tissue during parturition and abortion. Also, the junctional layer appears to function like a circular muscle layer, capable of peristaltic and anti-peristaltic activity, equivalent to the muscular layer of the intestines.
The perimetrium (or serous coat of uterus) is the outer serosa layer of the uterus (Pic. 5), equivalent to peritoneum. It is embrionically derived from visceral peritoneum. Perimetrium consists of superficial mesothelium, and a thin layer of loose connective tissue beneath it. Posterior surface of the uterus is completely covered by the perimetrium, but anterior surface only partially.
Medical condition characterized by the presence of ectopic endometrial tissue within the myometrium.
An eating disorder characterized by the maintenance of a body weight below average, fear of gaining weight, and a distorted body image.
A medical condition, where the walls of the uterus stick to one another due to bands of scar tissue.
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.
Thickening of the lining of the uterus.
The finger like overgrowths attached to the inner wall of the uterus that extend into the uterine cavity which are made of endometrial tissue
A state in which pieces of the tissue alike to the lining of the uterus (endometrium) grow in other parts of the body.
Hematosalpinx is a medical condition involving bleeding into the fallopian tube.
A hydrosalpinx is an abnormal pouch containing liquid in a fallopian tube.
A medical term which describes a diminished functional activity of the gonads – the testes and ovaries.
A surgery performed to remove a woman's uterus.
The time in most women's lives when menstrual periods stop permanently, and the woman is no longer able to have children.
An abnormal condition in a woman's menstrual cycle.
Light or infrequent menstrual ﬂow at intervals of 39 days to 6 months or 5–7 cycles in a year.
A form of abdominal adhesions in the pelvis.
Infection of the upper part of the female reproductive system and a common complication of some sexually transmitted diseases.
A distally blocked Fallopian tube filled with pus.
The absence of any developmental stage of sperm cell in the testes.
A medical condition impairing the function of the thyroid.
A permanent form of female sterilization, in which the fallopian tubes are severed and sealed or "pinched shut", in order to prevent fertilization.
The most common benign smooth muscle tumors of the uterus encountered in women of reproductive age.
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 form of a congenital malformation where the uterus is partially divided by a longitudinal septum. It is one of Müllerian duct anomalies.
The narrow inferior portion of the uterus that projects into the vagina.
The middle layer of the uterine wall, consisting of uterine smooth muscle cells.
Sex organ that is a part of the female genital tract having two primary functions: sexual intercourse and childbirth.
A multicellular diploid eukaryote in an early stage of embryogenesis, or development.
Cells composing an inner layer of the uterine lining.
A medical condition whose main symptom is low sexual desire.
Abnormally heavy or prolonged bleeding in menstrual periods.
Short or scanty periods with extremely light menstrual blood flow.
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).
Bleeding that occurs irregulary between the menstrual period.
Irregular menstruation is a menstrual disorder whose manifestations include irregular cycle lengths as well as metrorrhagia
The absence of sexual appetite.
The age at onset of first menstruation.
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.
Failure of implantation in at least three consecutive IVF attempts.
A disease distinct from infertility, defined by two or more failed pregnancies.
Retrograde flow of menstrual fluid through fallopian tubes into the pelvic cavity.