The female organ that produces eggs, or oocytes. Located on each side of the uterus, to which the ovaries are functionally connected by way of the fallopian tubes (or oviducts).

(PCOS) A syndrome that consists of polycystic ovaries associated with any clinical symptom or sign of too much male hormone effect, such as acne, excess body hair (hirsutism), or long or absent cycles (oligomenorrhea or amenorrhea). Often called polycystic ovarian disease in the US (PCOD).

Scar tissue, in particular between the serosa (surface lining) of abdominal or pelvic organs in the peritoneal cavity, which can interfere with the access the fallopian tube has to the ovary at ovulation. Adhesions can be thin and transparent (sometimes called filmy or Grade 1), a little like thin plastic wrap; thicker, and containing more scar tissue and blood vessels (Grade 2); or thick, dense and tough (Grade 3). Adhesions are caused by infections, endometriosis or a previous operation. Not all adhesions are important: it depends on where they are. See also intrauterine adhesions. The treatment of adhesions requires microsurgery, and there are special steps that have to be taken to stop them coming back again.

A weak androgen, produced in women by thecal cells in the ovary and by the adrenal glands.

A fluid-filled space between the follicle cells, the development of which marks the transformation of a tertiary follicle from a secondary follicle. Composes the bulk of the mature, preovulatory follicle (sometimes called the Graafian follicle) and very obvious on transvaginal ultrasound scanning during monitoring of follicular development as dark, "echolucent" spaces within the ovary.

Taking a small sample of tissue for diagnosis under the microscope. Biopsies of the endometrium can be done without anesthetic, through the cervix (see premenstrual biopsy). Biopsies of the ovary or of the lining of the peritoneal cavity (e.g. to detect subtle endometriosis) are done at laparoscopy. A testicular biopsy is done to determine why there's azoospermia. Using microscopic techniques, even an early embryo can be biopsied

A mucus-like protein produced in some circumstances by surface cells of tissues derived from the Mullerian ducts. Its function is obscure but measurement as serum CA125 antigen can be useful in diagnosing adenomyosis, endometriosis and some cancers of the ovary.

A cyst of the ovary caused by endometriosis. The name comes from the old, dehydrated and thickened blood that it contains. Often causes an increase in serum CA 125 antigen and can usually be seen on transvaginal ultrasound.

A drug that blocks the action of estrogens and so tricks the pituitary gland into thinking the ovary's follicles are not producing enough estradiol, so that natural FSH production is temporarily increased, the ovaries thereby are stimulated, and follicles grow. The LH surge and ovulation usually follow naturally, but human chorionic gonadotropin can be given if monitoring is used to make sure the follicle is properly mature. Brand names: Clomid (Marion Merrell) and Serophene (Serono)

(CAH) Enlargement and abnormal function of the adrenal glands, usually from before birth, owing to a genetically determined, partial block in the production of cortisol, the adrenal glands' main hormone, resulting in overproduction of subsidiary hormones, including androgens, tending to virilise the female fetus, which can present at birth with intersex. In mild forms does not manifest until puberty, when the symptoms of oligomenorrhea and hirsutism mimic those of polycystic ovary syndrome. See also serum 17-hydroxyprogesterone.

Latin for yellow body, the description being that of the solid or cystic structure in the ovary after ovulation. Derived from the ovulating Graafian follicle. At first red and friable as arteries and veins invade the collapsed follicle, it soon matures into a gland that is very efficient at producing progesterone, a hormone that's soluble in the fat and which therefore gives the corpus luteum its yellow color. Provides its name to the second, or luteal phase of the ovarian cycle, as well as to luteinising hormone, which causes the corpus luteum to be formed and sustains it until, in the event of pregnancy, it is supported instead by human chorionic gonadotropin. The appearance of the corpus luteum on transvaginal ultrasound is so variable (and so able to be confused with a serious abnormality of the ovary) that for accurate diagnosis of such pathology it is best to scan in the follicular phase or while taking a progestogen to prevent formation of this structure. Plural: corpora lutea.

A vaginal gel that contains 8%progesterone. Well absorbed and with a potent local effect on the endometrium. Used to mimic (or supplement) the ovarian luteal phase. A weaker (4%) formulation is available for longterm use in patients with polycystic ovary syndrome or after the menopause to prevent endometrial hyperplasia.

A pregnancy implanted in an abnormal location, such as the fallopian tube (see tubal pregnancy), the cervix (see cervical pregnancy), the ovary (see ovarian pregnancy) or the peritoneal cavity (see abdominal pregnancy).

Overgrowth of the endometrium, caused usually by prolonged action of estrogen unopposed by progesterone (i.e. prolonged anovulation), as is the case in, particularly, the polycystic ovary syndrome. Potentially dangerous, because it can turn to cancer of the endometrium. Can be suspected by an echogenic appearance of the endometrium on transvaginal ultrasound and is confirmed by pathological examination of tissue obtained at curettage.

The general name for one of the two principal female sex hormones (the other is progesterone), responsible for stimulating growth of the female reproductive system (the vagina, the cervix, the uterus and the fallopian tubes) and growth of the breasts. The main estrogen is estradiol, produced by: the developing follicle (and to a lesser extent by the corpus luteum) in the ovary; by the trophoblast of the placenta; and by the body's fat tissues (through conversion from male sex hormones, or androgens, in the blood). After the menopause the main estrogen is the weaker one, estrone, largely derived from conversion by the body's fat of the weak androgen androstenedione.

The hollow organ, about 10 to 12 centimeters long, that effectively joins the ovary to the uterus on each side. Composed of the fimbrial end, the ampulla, the isthmus and the interstitial segment.

Also "fimbriated end": the open, outside end of the fallopian tube in contact with the surface of the ovary, from which it "picks up" the ovulated egg from the ruptured follicle. It's composed of delicate fimbriae -- finger-like projections of the tube lined by cells with tiny hairs (cilia), which beat towards the inside of the tube, carrying the sticky cumulus mass containing the egg into the ampulla before fertilisation. Easily damaged by infection (salpingitis) or careless surgery, after which it may be blocked, resulting in a hydrosalpinx, or have its correct movement inhibited by adhesions.

Normal structure in the ovary that contains the egg, or oocyte. All are formed as primordial follicles before birth and remain microscopic in size until growth starts (folliculogenesis), a month or two before the cycle in which the particular follicle will be a candidate to ovulate. About 3 mm in diameter at the start of a cycle, and about 2 cm in diameter when ready to ovulate. The follicle makes more and more estrogen (particularly estradiol) as it grows. In ovarian monitoring for assisted conception, the number growing and their rate of growth are monitored by transvaginal ultrasound.

Serial transvaginal ultrasounds of the ovary during the follicular phase to track the growth of one or more tertiary follicles, accompanied usually by serial estimations of serum estradiol, serum LH and serum progesterone, for the two-fold purpose of estimating follicular maturity (to time intercourse, a mid-cycle-dependent investigation such as a postcoital test, or an egg retrieval) and identifying the onset of the LH-surge, which can affect the timing of the intervention. Sometimes accompanied by injection of human chorionic gonadotropin to trigger ovulation at a precisely anticipated time.

The part of the ovary's monthly cycle before ovulation, dominated by the presence of firstly, a cohort of growing tertiary follicles, then the dominant follicle, and the estradiol these follicles produce. Normally around 14 days in length, but quite variable, often being much longer for the first few menstrual cycles after the first period (menarche), and typically getting shorter in the months or years leading up to egg depletion and menopause. Corresponds with the proliferative phase of the endometrial, or menstrual cycle.

Not often carried out at no cost, "free" here means the androgen (testosterone) in blood that is not bound to carrier proteins such as sex hormone binding globulin, so it's immediately available for action in the tissues. A more sensitive test than serum testosterone and likely to be increased in the polycystic ovary syndrome. An indirect measure of serum free testosterone, which can be performed instead.

A gender-neutral word for an organ that contains germ cells and produces gametes, namely the ovary and the testis.

(LH) The hormone, or gonadotropin, produced by the pituitary gland to cause, in women, ovulation of a mature follicle in the ovary, resulting in formation of the corpus luteum; in men, stimulates the production of testosterone by the Leydig cells of the testis. Suppressed by GnRH-agonists and GnRH-antagonists, so that (for ovulation induction) an injection of human chorionic gonadotropin (hCG), which acts the same way, has a predictable time course of action. A small amount of LH is essential for normal function of the tertiary follicle and the corpus luteum. Recombinant LH is under development by Serono as Luveris, but its clinical role in place of hCG is not yet established.

A process similar to mitosis in which two successive divisions of a diploid cell's nucleus result in four 'daughter' cells, each with a haploid number of chromosomes. Unlike mitosis, each chromosome therefore duplicates just once (before the beginning of meiosis). Meiosis in humans (and other higher animals) takes place only among the germ cells (oogonia and spermatogonia, which will have been multiplying by mitosis. By differentiating into, respectively, primary oocytes or primary spermatocytes, each with 92 chromatids, meiosis commences. With completion of the first meiotic division the products (including secondary oocytes and spermatocytes) each contain 46 chromosomes. With completion of the second meiotic division the haploid number (23) of chromosomes, suitable for fertilisation, is reached. In the testis, meiosis and the production of new sperm cells (spermatozoa) can continue throughout life, but in the ovary all egg cells that survive commence meiosis about 20 weeks before birth, spending the remaining time (up to 50 years or more) locked up in primordial follicles as primary oocytes. Whereas a primary spermatocyte gives rise to four haploid sperm cells, a primary oocyte produces just one secondary oocyte (the spare 46 chromosomes are dumped into the first polar body just before ovulation), and then one egg cell (the spare 23 chromosomes are dumped into the second polar body after fertilisation).

Oral anti-diabetic drug that improves many aspects of the polycystic ovary syndrome, including lowering of androgens, serum LH, insulin levels and weight, in combination with a low calorie diet; improves development of ovarian follicles and ovulation, as well as responsiveness to clomiphene or gonadotropins if ovulation induction or in vitro fertilisation is necessary.

(pronounced 'mool-air-ian') Syn. paramesonephric duct. The internal female sex duct, which forms on each side of a female embryo to connect the peritoneal cavity with the outside of the embryo, starting at a point close to the ovary and forming first a fallopian tube then meeting its fellow from the other side to form the uterus, and then extending downwards to form the upper part of the vagina before finally connecting with a little dimple between the urethra (in front) and the anus (behind) to reach the exterior at the vulva. Passage of eggs from the ovaries (which ovulate into the peritoneal cavity of all vertebrate species) to the outside world through this duct is how animals, including humans, reproduce. In males the ducts do not develop because the Sertoli cells of the testes produce anti-Mullerian hormone.

The word pathologists use when there is death of part or all of a tissue or organ due to an outside factor, such as cutting off the blood supply. If apoptosis is regarded as cellular suicide, then necrosis could be called cellular murder. Important examples include aseptic necrosis of the femoral head and the loss of an ovary from untreated torsion.

The equivalent of the menstrual cycle in the ovary, comprising the follicular phase and the luteal phase. Thus the ordered sequence of timely development of tertiary follicles to a (usually) single dominant follicle or Graafian follicle, characterised by increasing production of the estrogen estradiol), through ovulation, when estradiol falls and progesterone starts to rise, followed by the development and then decline of the corpus luteum, with the further production of progesterone. Because estradiol and progesterone control the growth and development of the endometrium in the uterus, the ovarian cycle determines the menstrual cycle (normally lasting from 24 to 35 days in length, and with a typical duration of about 28 days) and also the cycle of the normal female hypothalamus and pituitary gland.

An ectopic pregnancy located in the substance of the ovary, presumably because an egg (an oocyte has been fertilised while still in a follicle).

Natural process by which a mature follicle in the ovary opens to release the secondary oocyte, or egg, enclosed in a sticky blob of mucus-like material, the cumulus mass.

Polycystic ovary disease.

(PCO) The full name (almost never used) is micro-polycystic ovaries: it's a diagnosis best made on transvaginal ultrasound, with lots of medium-sized follicles visible around the rim of the ovaries; can be part of the polycystic ovary syndrome. (The 'cysts' are not real cysts. Think of them as stalled follicles. They don't need to be treated.) A very common condition: about 20% of women have it, though only a few women have the full syndrome.

In medicine the word primary can denote primacy in one of 3 ways: (1) event-wise (e.g. primary amenorrhea is when there has been no precedent -- no prior period -- whereas secondary amenorrhea) follows prior periods, and likewise the distinction between primary infertility and secondary infertility, a distinction based on prior successful pregnancy); (2) developmentally or time-wise (e.g. a primary follicle gives rise to a secondary follicle, then to a tertiary follicle); or (3) causally (e.g. primary ovarian failure is based within the ovary itself, whereas secondary ovarian failure is secondary to failure of gonadotropins). These sort of distinctions is one reason why medical school takes a long time.

Failure of the ovaries to produce enough follicles, because of a problem in the ovary itself, and resulting in depletion of eggs before the age of 40 years (known as premature menopause, a cause of secondary amenorrhea), or maybe even before the age puberty is expected (causing failure of puberty to happen, including primary amenorrhea). Sometimes occurs in spite of good numbers of primordial follicles that (inexplicably, so far) won't develop. The younger the woman, the more likely that an aneuploidy will be found if a karyotype is done on blood or on a biopsy of the ovary. Estrogen replacement therapy is important to prevent general jeopardy to health, including prevention of osteoporosis.

The resting, unstimulated stage of the follicle, in which the egg (as a primary oocyte) is enclosed by just a few thinly stretched follicle cells. Primordial follicles persist in the ovary from fetal life to the time of menopause, declining in number every day during this time, as some start to develop into primary follicles, most of which then are lost through the process of follicular atresia. What the stimulus or signal is for a particular primordial follicle to start growing remains completely unknown (it is independent of FSH).

The ovary's second main hormone, produced only after ovulation and during pregnancy (first by the corpus luteum, then by the placenta). Sometimes administered by injection or by insertion into the vagina in the form of a pessary to supplement natural production.

17-hydroxyprogesterone is formed from progesterone in the adrenal glands (mostly as an intermediary substance on the way to making the adrenal's main hormone, cortisol) and in the ovaries (on the way to making androgens and estrogens). A congenital lack of one or other of the enzymes needed to make cortisol in the adrenal causes androgens to be made instead, in turn causing hirsutism and oligomenorrhea in women, maybe with the polycystic ovary syndrome (in mild cases), or (in severe cases) causing intersex at birth. The adrenal glands enlarge in an attempt to maintain production of cortisol (hence congenital adrenal hyperplasia, CAH). An inappropriately high level of 17-hydroxyprogesterone in serum is diagnostic of CAH.

Measurement of CA125 antigen in serum. A test done to investigate, particularly, adenomyosis and cancer of the ovary. Levels can also be increased with endometriosis (especially when there is a 'chocolate cyst' present), during normal menstruation and during normal early pregnancy.

Measurement of testosterone, the chief male sex hormone (androgen) circulating in the blood serum. If increased in women with oligomenorrhea or amenorrhea, indicative of the polycystic ovary syndrome. The free androgen index and free testosterone are more sensitive tests.

Infertility that is not 'absolute', or 'complete infertility' -- that is, there is a chance of pregnancy: it is not sterility (these last 3 terms are synonyms) -- but the chance of getting pregnant each month (fecundability or monthly fertility) is reduced. More or less definite causes can include oligospermia, polycystic ovary syndrome and other causes of oligomenorrhea, endometriosis, peritubal adhesions, fibroids (especially submucous fibroids) and increased age, especially of the woman. Synonymous with relative infertility.

A layer of cells in the ovary lying immediately around the follicle; under the influence of luteinising hormone it's responsible for producing the weak male sex hormone androstenedione, which is then (1) converted by the follicle cells (the granulosa cells) into estrogen, principally estradiol, or (2) converted by other tissues outside the ovary to testosterone.

Twisting of an organ on its vascular pedicle, risking necrosis. Can happen to the testis in boys, especially after an injury to the scrotum, or to the ovary and fallopian tube, either spontaneously during adolescence or when enlargement from superovulation has produced ovarian hyperstimulation syndrome (OHSS). An operation to untwist it can save the affected organ, if carried out quickly enough.

Intersex when tissue typical of an ovary and a testis is found in the one person. The genital organs can appear to be normal female, normal male, or somewhere in between. Intersex states where there are either normal ovaries or normal testes (but not both) are sometimes called pseudohermaphrodism.

A uterine anomaly that comes about when the uterus forms (in the embryo) from just one Mullerian duct; the uterus will be a little smaller than normal (making a miscarriage or premature labor more likely), and will be connected by a fallopian tube to just one ovary, contributing slightly to infertility (since, on average, only half of ovulations have a chance of resulting in pregnancy). Reproduction, however, can be normal, and a woman might go through life with a unicornuate uterus and not know it. Diagnosed by hysteroscopy and laparoscopy, by hysterosalpingogram or -- particularly effectively -- by three-dimensional ultrasound. Often there is a simultaneous abnormality of the kidneys, such as one kidney instead of two, diagnosable by abdominal ultrasound or, more specifically, by a special kidney x-ray study called an intravenous pyelogram.