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macroadenoma See pituitary tumor.

macrophage A cell in the body (a bit like the one-celled animal called an ameba) that’s able to: (1) wander about; (2) engulf and digest a huge range of foreign material and junk that gets into the body’s tissues (including sperm cells). They are present in almost every tissue in the body, especially if there is inflammation. We see them as scavenging cells -- the cells that do the ultimate tidying up inside the body -- but they can be programmed to swallow very specific targets, sometimes committing suicide for the greater good! There are normally lots of macrophages in the peritoneal cavity.

magnetic resonance imaging See MRI scan.

major histocompatibility complex An area of the genome where genes are found that determine your “tissue type”, important in determining whether, for example, you can accept or will reject an organ transplant from someone else. The genes in this area are tightly packed, show extreme polymorphism, and tend to be inherited together as a group.

maturation arrest See azoospermia and spermatogenesis.

media Plural of medium. See culture medium.

medical vocabulary See vocabulary.

medium See culture medium.

medroxyprogesterone acetate (MPA) A progestogen of a type related to progesterone itself. Marketed as Provera (tablets) and Depo-Provera (injections) by Upjohn.

meiosis 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 fertilization, 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 fertilization). See also chromosomal cross-over.

membranes The amniotic membrane and the chorionic membrane attached to the placenta.

menarche The first natural menstrual period (pronounced “menarcky’).

Menogon Highly purified human menopausal gonadotropin made by Ferring, and comparable to Metrodin HP. Called Repronex in the US. Not available in Australia.

menopause The last natural menstrual period (so often a retrospective diagnosis); hence the adjective menopausal, the natural state a woman is in after the ovaries have stopped ovulating because of depletion of eggs. The normal age of menopause is between 40 and 55 years, with an average in Western societies of 50-51 years. See also perimenopause, premature menopause, oopause and estrone.

menorrhagia Traditional medical term for dysfunctional uterine bleeding, or, simply, heavy periods.

menstrual abortion See menstrual miscarriage.

menstrual cycle The ovarian cycle as it’s expressed by the endometrium of the uterus. It consists of the menstrual phase, the proliferative phase and the secretory phase. Like the ovarian cycle itself, it’s normally 24 to 35 days in length -- typically 28 days, but there are lots of normal exceptions.

menstrual miscarriage For our purpose in the book, the loss of an early embryo at or before the expected time of a period. Not noticeable without specially measuring levels of serum human chorionic gonadotropin One form of so-called biochemical pregnancy.

menstrual phase The phase of the menstrual cycle in the endometrium during which there is menstruation, caused by withdrawal of progesterone at the end of the ovarian luteal phase as a new ovarian follicular phase starts; in anovulatory cycles or during treatment with estrogens, menstrual bleeding can occur from withdrawal, insufficiency or downward fluctuations of estrogen alone.

MESA See microepididymal sperm aspiration.

mesoderm The third, or “middle” layer of the developing tissues of the early embryo, forming between the ectoderm and the endoderm during the transformation of the embryo known as gastrulation; mesoderm gives rise to the body's muscles, bones and various connecting tissues.

mesonephric duct cyst See mesonephric duct.

mesonephric duct A duct on each side of the developing embryo or fetus that leads from the embryo’s mesonephros, or temporary kidney. In male fetuses the duct persists as the Wolffian duct to form the rete testis, the epididymis, the vas deferens and the seminal vesicle. In female fetuses it usually disappears completely (in favor of the paramesonephric duct, better known as the Müllerian duct), though portions of mesonephric duct can remain as harmless cysts, called Gärtner’s duct cysts.

mesonephric remnant See mesonephric duct.

metaphase The third stage (of four stages) of mitosis (or meiosis), at which the chromosomes, attached in a plate-like formation to a structure in the cell called a spindle, are easily distinguished with a microscope, and can be photographed to construct a karyotype.

metaplasia The metamorphosis of a tissue to take on a different form, perhaps more characteristic of a tissue some distance away. One of the theories of the cause of endometriosis is based on metaplasia. The controversy is discussed in the box, Implantation or metaplasia?, in WebPage 15.

metformin 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 fertilization is necessary.

methotrexate A cytotoxic drug, originally developed for chemotherapy for certain cancers, used in the treatment of ectopic pregnancy, especially in the US; side effects can include bone marrow depression, gastrointestinal upset and mouth ulcers, and other effects.

Metrodin HP. Called Fertinex in the US. Metrodin that has been highly purified by removing all contaminating urinary proteins and all luteinizing hormone, and is thus similar in action to recombinant follicle stimulating hormone. See also serum estradiol and ultrashort protocol.

Metrodin Human menopausal gonadotropin (hMG) from which luteinizing hormone (LH) has largely been removed, leaving follicle stimulating hormone (FSH) as the active substance. Metrodin HP (Fertinex in the US) is more purified, other urinary proteins having been extracted too, and (unlike Metrodin) has no LH activity at all. Made by Serono.

metroplasty A plastic operation on the uterus to change the shape of its cavity, usually for a uterine septum or for a bicornuate uterus, if there have been a number of miscarriages. Illustrated and described in WebPage 18.

metrorrhagia Traditional medical term for intermenstrual bleeding.

MHC See major histocompatibility complex.

microadenoma See pituitary tumor.

microchimerism A state in an embryo, fetus, animal or person in which a small number of cells occur that have a different genome. Arises naturally because cells (rarely, stem cells) can cross between a mother and her fetus, or experimentally by introducing foreign stem cells into an embryo, usually at the stage of blastocyst, when the introduced cells become part of the inner cell mass.

microepididymal sperm aspiration (MESA) Using microsurgery to dissect the epididymis or rete testis (or sometimes the tubules of the testis itself -- see also testicular sperm extraction) to find motile sperm cells suitable to be aspirated, isolated and prepared for an in vitro fertilization procedure, usually involving sperm microinjection, especially intracytoplasmic sperm insertion.

microsurgery Literally, operating on small organs and tissues under the magnification provided by an operating microscope; the magnification is typically in the range of 6-16x for infertility surgery. The term also implies keeping the tissues wet with physiological salt solution during the operation, using fine, non-reactive stitches or sutures, being meticulous about stopping bleeding from small blood vessels, and avoiding trauma to the serosa. See also fimbriolysis, microepididymal sperm aspiration, salpingolysis, salpingostomy, and sterilization-reversal (which includes tubal anastomosis and vasovasostomy).

minilaparoscope An instrument for carrying out laparoscopy that is just a few millimeters in diameter, making it possible to perform such operations in an ambulatory setting, without general anesthesia. The reliability of diagnoses made this way will need careful evaluation, especially if done to exclude endometriosis, which can be difficult to find even with conventional laparoscopy.

miscarriage The delivery of (or the process of delivering) a conceptus before there is a viable fetus. See also threatened miscarriage, inevitable miscarriage, incomplete miscarriage, complete miscarriage, menstrual miscarriage, subclinical miscarriage, missed abortion and recurrent miscarriages.

miscarriage rate The percentage chance that a pregnancy will end as a miscarriage. The normal rate of clinically apparent miscarriage for young women is about 12 percent. The rate rises independently with age, the number of previous pregnancies, and especially the number of previous miscarriages experienced. The rate is also higher with many causes of infertility when conception occurs with or without treatment. The chance of having a second miscarriage after the first is described in the lengthy but important box, Malpas's mistake, in WebPage 9.

missed abortion A miscarriage that should have happened but hasn’t. As a result, the pregnancy tissue in the uterus gets tougher and more difficult to get out with a uterine curettage -- which is the only treatment for it, but risks producing intrauterine adhesions. The pregnancy test can stay positive for many weeks or even months.

missed miscarriage See missed abortion (in this context one still rarely hears the word “miscarriage’).

mitochondria Plural of mitochondrion.

mitochondrion A tiny structure inside the cell resembling a bacterium and responsible for burning food molecules with oxygen to produce carbon dioxide, and thus providing energy for the cell’s use. Each cell has hundreds or thousands of mitochondria. If there’s a single aspect of a cell that reveals the process of aging, it’s the mitochondria, which get less efficient as a person (and specifically a tissue) gets older. Mitochondrial aging in egg cells could be the reason why eggs in women over the age of 40 so often seem unable to produce healthy embryos -- an intriguing area of current research (see mtDNA and read the box, How eggs might get their “use-by” date: Mishaps in the mitochondria, in WebPage 7.

mitosis Usual process by which a cell (more strictly the nucleus of a cell) divides into two. Each chromosome duplicates before the beginning of mitosis, and mitosis involves separation of the resulting duplicates so that one goes into each “daughter” nucleus [adapted from The Penguin Dictionary of Biology, 6th edition, Penguin Books Australia Ltd, Ringwood, Victoria, 1973]. At the third stage (of four stages) of mitosis, called metaphase, the chromosomes are easily distinguished with a microscope, and can be photographed to construct a karyotype. See also meiosis.

Mittelschmerz German for ovulation pain.

mixed reproductive loss Repeated loss of pregnancies at different stages of development of the embryo or fetus, i.e. at different stages of pregnancy. Related to recurrent miscarriages.

mixoploidy An abnormal state of the chromosomes seen on a karyotype in which cells from an individual display two or more genetically different chromosome pattern. Can be the result of mosaicism or chimerism.

monitoring In our context, the frequent estimation of serum estradiol (or perhaps estimating the cervical score) and performance of transvaginal ultrasound to estimate how close a woman is to ovulation. Monitoring is described in detail in WebPage 20. See also serum LH and serum progesterone.

monoamniotic twins Identical or monozygotic twins in which the split has occurred after formation of the blastocyst, so that the twins share the same gestational sac (or amniotic cavity). There is a much higher risk of complications than in the more usual situation where twins do not share the same sac, because the fetuses or the umbilical cords can get tangled up.

monosomy An abnormality of the chromosome number due to a loss of one chromosome from a diploid set, resulting in 45 chromosomes instead of 46. The only mosomy compatible with fetal development and continued survival is that of Turner syndrome, the karyotype of which is 45,X (i.e. a monosomy of the sex chromosomes).

monozygotic twins Twins formed from the splitting of a single fertilized egg, or zygote; identical twins; see also monoamniotic twins.

monthly fecundity American for the monthly chance of conception, or monthly fertility rate. See also fecundability.

monthly fertility rate The monthly chance of conception, the technical term for which is fecundability. See also normal monthly fertility.

monthly fertility See monthly fertility rate.

morula A stage of the embryo that consists of a ball of cells, still enclosed by the zona pellucida, before the next stage of blastocyst. Formed from the fertilized egg, or zygote, by the processes of cleavage and compaction.

mosaicism The condition when an individual shows two or more genetically different cell lines (generally with different karyotypes) that are derived from one zygote. See also chimerism and mixoploidy.

motility The quality of movement, especially forward propulsion, shown by sperm cells (spermatozoa) and caused by effective beating of their tail, or flagellum. Analyzed as part of the routine sperm count.

MRI scan Magnetic resonance imaging is a special form of imaging the body’s internal structures, taken with the person enveloped in a huge and powerful magnet; a picture is built up of any cross-section, or series of cross-sections, through the body, using a technique that detects and pictures structures by their different content of atoms with certain resonances to induced magnetic fields. Particularly useful for investigation of the anatomy of the pituitary gland and hypothalamus when a tumor is suspected. More expensive and less widely available than a CT scan, which gives adequate results in most cases.

mtDNA Mitochondrial DNA. The small amount of DNA found in the mitochondria. mtDNA is the genetic code for 13 proteins involved in metabolism. Because mtDNA is much less stable than the DNA in the chromosomes (where the huge bulk of genetic code is stored), mutations accumulate with time at a greater rate than that for chromosomal DNA -- and eventually limit how well a particular cell or tissue can function with increasing age. Because all of the mtDNA you have you inherited from your mother (you derive your mitochondria from the egg you came from), we could have an explanation: (1) why all eggs are formed before birth (so the mitochondria don’t have to keep on dividing too often and risking genetic errors); and (2) why miscarriages and infertility get commoner with age (as the egg’s several thousand mitochondria begin to succumb to genetic errors).

MTHFR C677T A polymorphism affecting the metabolism of folic acid with a number of possible consequences avoidable by increasing dietary supplements to mega-doses (5 mg to 10 mg per day), including promotion of blood coagulation, or thrombophilia, abnormalities of the fetus (birth defects, especially neural tube defects such as spina bifida and anencephaly), recurrent miscarriage, an increased chance of heart disease and coronary thrombosis, and in men, possibly contributes to oligospermia and infertility.

mucus Jelly-like secretion that is at once both sticky and slippery. See cervical mucus and cumulus mass.

Müllerian duct (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. Oddities in the development of the ducts cause congenital anomalies of any or all of these organs and are described in WebPage 18. In males the ducts do not develop because the Sertoli cells of the testes produce anti-Müllerian hormone. See also mesonephric duct.

Müllerian inhibiting factor See Müllerian duct.

myoma See fibroid.

myomectomy An operation to remove a myoma, or fibroid. A myomectomy for a submucous fibroid is often possible at hysteroscopy; a myomectomy for an intramural fibroid (located within the wall of the uterus), usually requires an open operation, or laparotomy; a myomectomy for a subserous fibroid can be possible at laparoscopy.

myometrium The muscular wall of the uterus, surrounding the endometrium. The myometrium contracts (1) during menstruation perhaps causing dysmenorrhea, and (2) during miscarriage or labor to deliver the conceptus. See also myoma (or fibroid) and adenomyosis.

 

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nafarelin A GnRH-agonist, made by Syntex as Synarel and used as a nasal spray.

natural killer cells See NK cells.

naturalistic fallacy The philosophical term coined by G.E. Moore early in the twentieth century to devalue drawing ethical conclusions from empirical observation -- i.e. by moving from what is (facts that are observed) to what ought (morality). Moore felt that ethics should be intuitive, not inferred -- therefore he presumably favored deontological ethics over teleological ethics. Practical ethicists find this constraint unnaturally crippling as it prevents them making a value judgement.

necrosis 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, which is described in the box, Twisted ovaries, in WebPage 12 as a complication of ovarian hyperstimulation syndrome (OHSS).

negative history If you have a negative history for a disease or symptom it means that you do not have or have not had that disease or symptom. Compare with positive history.

negative test In medicine generally it may be best for tests to be negative (like tests for brain tumors or tests for sexually transmitted diseases such as HIV -- as for “histories’, compare negative history), but this is not always so in infertility. Infertility tests are generally better if they’re positive, like the postcoital test, tests for ovulation, tests for tubal patency, and (not least) a pregnancy test (see also positive test).

NET See norethisterone.

neurohypophysis The neural (nerve-containing tissue) part of the pituitary gland, lying towards the back … and so, in medical speak, called the posterior pituitary. Produces the hormones oxytocin (which acts on myometrium to cause contraction of the uterus) and vasopressin (which helps maintain blood pressure and conserves the body’s water in the kidneys).

NK cells White blood cells or lymphocytes that form part of the “innate” immune system capable of recognizing foreign cells and dissolving them (hence their name: natural killer cells). Found normally, however, in the endometrium of the late secretory phase and in the decidua of pregnancy, where they have more friendly purposes in forming the boundary between mother and fetus. Unlike T cells and B cells, most NK cells do not have “immunological memory”, whereby previous contact with a particular antigen causes a faster, more deadly immune response second time round.

non-maleficence The ethical principle that comes from not doing harm. See also beneficence and suffering.

non-obstructive azoospermia Azoospermia caused by low sperm production rates in the testis, including maturation arrest. Can often be overcome with testicular sperm extraction (TESE) followed by in vitro fertilization utilizing intracytoplasmic sperm insertion (ICSI).

norethisterone (NET) A progestogen of a type weakly related to the male hormone testosterone. Progestogens of this class are commonly found in the oral contraceptive pill. Norethisterone acetate is marketed as Primolut N and is made by Schering. Called norethindrone in the US.

normal monthly fertility Nature gives fertility a wide range, normally from about 7 to 45 percent per month for women in their early twenties, to about 3 to 25 percent per month for women in their early 30s; for women in their early 40s, it ranges from less than 1 to about 5 percent per month. See also monthly fertility and fecundability.

Novarel Preparation of hCG made by Ferring. Similar to Pregnyl and Profasi.

NSAIDs Nonsteroidal anti-inflammatory drugs, e.g. aspirin, ibuprofen (Advil, Nurofen etc), mefanamic acid (Ponstan), naproxen sodium (Aleve, Naprosyn, or in Naprogesic in combination with dextropropoxyphene), which stop the production of prostaglandins; useful for dysmenorrhea and prior to a hysterosalpingogram. Excessive use at the time of ovulation might predispose to a luteinized unruptured follicle, so NSAIDs should not be used for ovulation pain if you are trying to get pregnant.

nuchal lucency See nuchal translucency.

nuchal thickness See nuchal lucency.

nuchal translucency A measurement done at transvaginal ultrasound of tissue in the neck of the fetus; if excessive, it implies a substantially increased risk that the fetus is affected by Down syndrome and Turner syndrome.

nucleus Central structure within a cell that contains the chromosomes. The non-nuclear part of the cell is called the cytoplasm -- which thus contains other cellular structures, including the mitochondria. Genetic inheritance is mostly by way of the nucleus (with a contribution from mother and father); a small part is by way of the cytoplasm (with a contribution only from the mother). See also mtDNA and mitosis. Plural: nuclei.

 

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obligation A moral compulsion for ethical action, sometimes usefully distinguished from a duty by its derivation from example or external enforcement. According to this distinction, obligations are derived chiefly from the considerations of teleological ethics and utilitarian ethics, with duties derived from considerations of deontological ethics. See also rights.

obstructive azoospermia See azoospermia.

oestrogen See estrogen.

oestrone See estrone.

office biopsy See premenstrual endometrial biopsy.

OHSS See ovarian hyperstimulation syndrome.

oligomenorrhea Infrequent menstrual periods. By convention, a menstrual cycle that is consistently longer than 35 days. Oligomenorrhea always reflects irregularity of hormonal events coming from the ovaries. See also anovulation and amenorrhea.

oligospermia Strictly, oligozoospermia, meaning a reduced number of sperm cells (spermatozoa) in the ejaculate (compared with azoospermia, which means no sperm in the ejaculate). More generally, a decrease in normal, motile sperm, and more or less encompassing laborious terms such as “asthenozoospermia” (weak motility) and “teratozoospermia” (abnormal sperm), and even more laborious ones, such as “oligoasthenoteratozoospermia’, which do not reward the effort of concocting them.

oocyte The form of the ovum, or egg, which is undergoing a halving of the number of chromosomes through the process of meiosis; see also primary oocyte and secondary oocyte.

oogenesis The multiplication (by the process of mitosis) of ova, or eggs, in the ovaries of the fetus.

oogonium The earliest recognizable form of the ovum, or egg; present only in the ovaries of fetuses. Multiplies by the process of mitosis before developing into oocytes by the process of meiosis. The male equivalent (the spermatogonium) normally persists in the testicles till old age. Plural, oogonia.

oopause A new term for the normal cessation of female fertility up to 10 years before the menopause, being apparent in some women after the age of 33 and most women by 45. Different from the perimenopause, which occurs as egg numbers fall far enough to cause shortening of the menstrual cycle, particularly the follicular phase, and accompanied by elevation of serum FSH when measured during menstruation. If pregnancies are attempted through the oopausal transition, a woman who has had no prior reproductive disturbance will typically experience recurrent miscarriages before developing otherwise unexplained infertility, manifesting in the IVF lab sequentially with unexplained implantation failure of apparently satisfactory embryos, then, in turn, a decreased rate of forming blastocysts, defective cleavage, and then failure of fertilization. There is no known method of overcoming its effects short of egg donation, except for some hope that the procedure of cytoplasmic transfer might be helpful.

oophorectomy See ovariectomy.

OPU Ovum pick-up: see follicle aspiration and egg retrieval.

orchidopexy An operation to move an undescended testis into the scrotum, so that it has more chance of developing normally and producing sperm cells (spermatozoa). See also cryptorchidism.

Orgalutran The GnRH-antagonist ganirelix made by Organon. Called Antagon in the US.

orgasm I don’t need to tell you what this is, you can find out for yourself! What you might like to read about it, though, is how having one, or not having one, or having one early or late, affects getting pregnant. Read the box, Orgasm and retaining sperm, in WebPage 19.

osteoporosis An abnormal condition of the bones, which are weakened by a loss of calcium. Deficient estrogen, such as after the menopause or after primary ovarian failure (premature menopause), eventually causes osteoporosis, with a tendency to bone fractures, especially of the wrist, the thigh and the backbone.

ovarian cycle 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, characterized 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.

ovarian hyperstimulation syndrome (OHSS) A complication of ovulation induction with, usually, follicle stimulating hormone, especially in cycles of superovulation for assisted conception, when it is intended to retrieve more than one egg. The ovaries become large, they can be painful, and there is excessive fluid released into the abdomen (the peritoneal cavity). Either removing this fluid or the occurrence of vomiting can cause dehydration, thickening of the blood and, occasionally, a serious thrombosis, such as a stroke. Death has been reported. Moderate to severe OHSS is treated in hospital, with administration of fluid intravenously, sometimes including albumin. See also vascular endothelial growth factor.

ovarian monitoring The frequent estimation of serum estradiol (or perhaps estimating the cervical score) and performance of transvaginal ultrasound to estimate how close a woman is to ovulation. Monitoring is described in detail in WebPage 20. See also serum LH and serum progesterone.

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

ovariectomy Surgical removal of the ovary. If the other ovary remains, the ovarian cycle, ovulation and the menstrual cycle usually continue as before. The place of ovariectomy in the management of endometriosis and incapacitating premenstrual tension is discussed in WebPage 16. Synonym: oophorectomy.

ovaries See ovary.

ovary 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).

Ovidrel Recombinant human chorionic gonadotropin made by Serono. Called Ovitrelle in Europe.

oviduct Another name for fallopian tube (derived from its function of conducting, or transporting, the ovum).

ovulation 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). See also luteinizing hormone, LH surge, ovulation pain and human chorionic gonadotropin. Understanding the normal processes of reproductive physiology forms the basis for WebPage 3.

ovulation induction The use of drugs to stimulate the development of follicles in the ovaries to undergo ovulation, such as clomiphene, various preparations containing follicle stimulating hormone (FSH), and human chorionic gonadotropin (hCG). The two main situations for it are: in the treatment of infertility due to anovulation (typically when there is oligomenorrhea or amenorrhea (described in WebPage 11); and for superovulation in assisted conception (e.g. in vitro fertilization and gamete intrafallopian transfer (described in WebPage 20). See also ovarian hyperstimulation syndrome and ovarian monitoring.

ovulation pain A mild pain that precedes ovulation by about 12 hours, felt in the left or right side, but not by everyone or in every ovarian cycle. A good indication of ovulation if it is felt. Can be exaggerated in endometriosis and in so-called pelvic congestion. The time from ovulation pain until the onset of menstruation (ignoring for this purpose any premenstrual spotting) is a good measure of the length of the luteal phase. Should not be treated with NSAIDs such as Advil or Nurofen if you are trying to get pregnant, because these analgesics have been linked to the so-called luteinized unruptured follicle syndrome, or LUF.

ovulatory dysfunctional uterine bleeding Heavy but generally regular bleeding caused either by pathology in the uterus, such as fibroids, or by a generalized bleeding disorder, such as thrombocytopenia (a low platelet count), von Willebrand’s disease (can run in families), or treatment with anticoagulant drugs. The formal term for it is menorrhagia.

ovum The female germ cell, or egg, from the earliest stage (the oogonium in the fetus), through its release from the follicle (ovulation), and (to professional embryologists) through fertilization up to and sometimes beyond the stage of implantation. See also blighted ovum. Plural: ova.

ovum pick-up (OPU) See follicle aspiration and egg retrieval.