White blood cells or lymphocytes that are part of the immune system concerned with recognising and dealing with foreign or abnormal cells discovered in the body's tissues.

The percentage of treatment months (or treatment cycles in assisted conception) that result in the woman taking home one or more babies (twins are not counted separately, though!); the statistic of most interest to patients and, in an age of skepticism in the community, the most politically correct statistic for reproductive medicine clinics to quote, but it's less useful for clinics' quality control purposes than the conception rate, the implantation rate, and the viable pregnancy rate, because: (1) it excludes obstetric misadventures often beyond the control of the infertility clinic; and (2) there is a long lag before it can be calculated, making results at best about 9 months old.

A set of ethical beliefs based on the goodness or badness of consequences, whether actual, intended or predicted. For purposes here, restricted to consequences to individuals, in contrast to utilitarian ethics. Open to change according to empirical observation of outcomes (hence 'evidence based ethics').

The third stage of growth of the follicle, in which the egg is enclosed by a thick layer of round-shaped follicle cells among which an antrum, or fluid-filled space, has formed; this antrum will come to dominate the size of the follicle. The first stage of the follicle visible with transvaginal ultrasound (when it reaches about 4 mm in diameter). Further growth of the early tertiary follicle is determined by follicle stimulating hormone. Synonym: antral follicle.

Plural of testis.

Diminutive of testis: the terms are interchangeable.

A biopsy of the testis to work out the reason behind an absence of sperm cells (azoospermia). Also used for testicular sperm extraction (TESE).

A state of intersex in which the karyotype is male (i.e. 46,XY), the gonads are testes (hence also male), but the body is completely unresponsive to testosterone and to its metabolite dihydrotestosterone, so it develops in the female way, with a normal vulva and vagina apparent at birth, and with normal development of the breasts at puberty. Because the testes still secrete anti-Mullerian hormone, there's no uterus. Invariably these children are raised as girls, normal except for their primary amenorrhea and their infertility. Specialist medical supervision is needed, because there is an increased risk of cancer in the abnormal gonads. Synonymous with androgen insensitivity syndrome (complete form).

(TESE) Dissection into the testis itself, in men with azoospermia due to maturation arrest, to recover (by 'teasing out') immature sperm cells from the (often small) fraction of testicular tubules there which still contain such cells. The sperm cells are used for in vitro fertilisation using intracytoplasmic sperm insertion (ICSI).

The main constituent of the testis, lined by Sertoli cells and containing the developing sperm cells. Lying between the tubules are the interstitial or Leydig cells.

The male gonad, located normally in the scrotum. Produces the hormone testosterone as well as the male germ cells, or spermatozoa. Interchangeable with testicle. Plural: testes.

The main male sex hormone, or androgen, in the blood (where it is measured as serum testosterone). Secreted in large amounts by the testis in a man. Before it acts on the tissues it must be converted to dihydrotestosterone. Present also in women, being converted from the weaker androgen androstenedione.

Tests that check if the fallopian tubes are open, usually by passing fluid through the cervix to fill the endometrial cavity and then demonstrate it coming out the ends of the tubes. The two common tests are to pass a blue dye at laparoscopy or a solution opaque to x-rays, namely a hysterosalpingogram. Once upon a time, carbon dioxide gas was used and listened for with a stethoscope (a Rubin's test); a high-tech version of Rubin's test uses transvaginal ultrasound to show the gas.

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.

Cells that make up, or come from, the theca interna.

The use of somatic cell nuclear transfer to produce embryonic stem cells suitable for differentiation into tissues that are a perfect match to treat disease in the person who provided the cell nucleus used. Ethically controversial.

Traditionally, any bleeding from the uterus during pregnancy while the cervix is (still) closed. Today, as well, there would need to be a normal embryo and, a little later, normal fetal heart movement pattern on transvaginal ultrasound to separate it from an inevitable miscarriage.

A computer enhanced transvaginal ultrasound or a multi-probe abdominal ultrasound that produces a composite, constructed three-dimensional image of the uterus, which can then be viewed from any perspective. Excellent for displaying the form of the uterus in the investigation of uterine anomalies and recurrent miscarriages.

An enzyme present in the blood that, when activated by tissue injury, causes blood to clot.

An increase in the tendency of the blood to clot, as in 'thrombosis'. In primitive, evolutionary times, a survival advantage for women giving birth, when loss of blood would on average be less, but exacting a price in terms of increased risk of stroke or venous thrombosis. The thrombophilias are implicated in disturbances of pregnancy, including recurrent miscarriage and stillbirth.

(TFTs) Usually two tests: a serum thyroxine (low for underactivity, high for overactivity) and a serum thyroid stimulating hormone (TSH, high for underactivity based primarily in the thyroid gland, low for overactivity based primarily in the thyroid gland and low for underactivity based in the pituitary gland). As a screening test for malfunction of the thyroid gland a serum TSH will generally be enough.

(TSH) A hormone produced by the adenohypophysis (the front, glandular part of the pituitary gland) that switches on the thyroid gland, causing it to make and release thyroxine.

The main hormone of the thyroid gland, responsible for controlling the rate of metabolism in the body; activity of the thyroid gland is measured with thyroid function tests.

One of the two most important variables that determine the chance of still getting pregnant naturally in subfertility and unexplained infertility (the other is duration of infertility). The longer the time still available the better the chance that, sooner or later, pregnancy will happen. Broadly limited by the female partner's age, but personal circumstances and ambitions within the biologically available timeframe might shorten it, leading to a decision to seek treatment with assisted conception.

An estimate of likely fertility in secondary infertility, where the time it took to get pregnant the first time is used as a very approximate guide to what might be expected next time round. Of limited usefulness, but if it took a long time to get pregnant the first time it will typically take at least as long next time. Achieving a pregnancy does not usually itself permanently cure subfertility.

Abbreviation for threatened miscarriage.

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.

Surrogacy in which the woman who is the surrogate for the intended pregnancy provides the eggs (through her own ovulation); is impregnated by assisted insemination; carries (or 'gestates') the pregnancy; gives birth; and then gives up the baby to the person who commissioned the surrogacy arrangement. Also known as genetic-plus-gestational surrogacy. The surrogate is as much the biological mother of the child as if she had conceived in natural circumstances, except that the male by whom she has been impregnated has no prior social relationship with her. No countries other than the US, where commercial surrogacy can be legal, have encouraged the practice, whether for altruistic or commercial reasons.

An individual with a gender identity that is opposite to that conventionally associated with his or her biological sex. Not to be confused with intersex or with sexual preference.

Ultrasound imaging of the pelvic organs for diagnosing abnormalities of (particularly) the uterus and the ovaries; for monitoring the development of ovarian follicles with ovulation induction and assisted conception programs; and for following the course of early pregnancy. Among the pioneers were Dr Karl Popp, who used a mechanical sector scanner vaginally in Hamburg in 1984, and Dr John Anderson, who used the first vaginal linear array scanner at Sydney IVF in 1985, leading to its widespread use subsequently in Australia and the US.

Literally, a three-month period of time; so the nine months of pregnancy are divided into the first, second and third trimesters. Most miscarriages take place in the first trimester (up to 12 or 13 weeks). Pregnancies that reach the third trimester (beyond 27 weeks) have an increasingly good chance of being viable (though nowadays, with intensive care, survival has occurred from about 24 weeks).

A screen for congenital abnormalities of the fetus done on the mother's blood serum during pregnancy to look for fetal trisomy, including Down syndrome. The original test comprised measurements of (1) serum alpha fetoprotein (decreased in the trisomies), (2) serum hCG (increased in trisomy 21, decreased in trisomy 18), and (3) serum estriol (decreased in trisomy 21, increased in trisomy 18). Note that only 60% of pregnancies with Down syndrome will be revealed by a triple test. Refinements have taken place, with 'free beta' (part of the hCG molecule) replacing hCG itself, and with the addition of PAPP-A replacing estriol, increasing the sensitivity and specificity of the test. Further gains in sensitivity and specificity comes from adding an ultrasound test for nuchal translucency. Even so, false positive tests are possible, which will be resolved only by performing CVS or amniocentesis, and so also are false negative tests, which means that CVS and amniocentesis should still be considered in otherwise high-risk situations.

A trisomy with a karyotype of 47,XXX -- a female with an extra X-chromosome. The old description of 'super female' is misleading, because fertility, if affected, is most likely reduced; primary ovarian failure is more common than with a normal chromosome complement and premature menopause then follows.

A state of 69 chromosomes, or three times the haploid number, most commonly caused by fertilisation of the egg with two sperm; the embryo that results can develop as far as a fetus, but is doomed to miscarry. The trophoblast of the placenta often undergoes partial changes of a hydatidiform mole. The noun form for this adjective is triploidy (the state of being triploid).

A GnRH-agonist marketed by Ipsen Biotech as Decapeptyl.

An abnormality of the chromosome complement in which there is an extra chromosome seen on the karyotype. The extra chromosome can be an autosome, such as in Down syndrome (trisomy 21), or a sex chromosome, such as triple-X syndrome (47,XXX), Klinefelter syndrome (47,XXY) and extra-Y-chromosome syndrome (47,XYY).

A trisomy for chromosome number 21, or an extra chromosome-21. This is the most common of the trisomies and gives rise to Down syndrome. Research has shown that the commonest source of the extra chromosome is a mistake in the first division of meiosis in the egg cell (during the many years it rests as a primary oocyte).

Group of cells that differentiates around the periphery of the developing embryo when it is a blastocyst and which will, if all goes well after implantation, form the placenta and membranes.

As the cells of the early embryo specialise, they soon differentiate into: (1) central ones that will form the embryo or fetus itself; and (2) peripheral ones (the trophoblast) that will be responsible for invading the mother's tissues (see implantation) and will form the placenta and the membranes.

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 self-evident ethical principle, which has value provided no substantial harm is done; not to be dispensed with for expediency alone.

A tubal ectopic pregnancy that is in the process of being expelled out the fimbrial end of the fallopian tube.

Microsurgery of the fallopian tubes in which an area of blockage is cut out and the healthy bits of tube on each side of the blockage are sewn back together. Can be done for localised salpingitis, including salpingitis isthmica nodosa, and for sterilisation reversal.

Overcoming a localised obstruction of the isthmus or the interstitial segment of the fallopian tube by pushing a wire or a catheter through it, enabling (in some cases) the tube to be 're-canalised' and so to remain open after being blocked before; it's an attractive alternative to tubal anastomosis and can be performed either during the investigation of tubal infertility with hysteroscopy, laparoscopy and falloposcopy or at the time of carrying out a hysterosalpingogram. Because not all tubes that seem to be blocked are in fact blocked (sometimes a normal tube will not allow fluid to pass through it for hormonal reasons or because of a spasm), care needs to be taken to investigate the tube properly before canalisation is undertaken.

(TEST) A variation of zygote intrafallopian transfer (ZIFT) in which, usually a day after when ZIFT (or PROST) would be carried out, cleaving embryos (at a two-cell to four-cell stage) are transferred to the fallopian tube as part of an in vitro fertilisation program.

A sterilisation operation in a woman involving interruption of the fallopian tubes.

An ectopic pregnancy located in the fallopian tube; most occur in the ampulla, but others can be located in the narrower isthmus or in the interstitial segment.

For those of the testis.

The combination of primary ovarian failure with constitutional (that is, genetically determined) shortness; often with other clinical abnormalities, including 'webbing' of the neck; an increased 'carrying angle' at the elbow; short fourth metatarsal (feet) and metacarpal (hand) bones (the bone within the hand that leads to the ring finger), and sometimes abnormalities of the heart and the thyroid gland. Associated with a karyotype that is 45,X (a monosomy, with one sex chromosome missing) or with partial loss ('deletion') of one of a pair of X-chromosomes. The single X-chromosome present can come from the mother or the father -- and, interestingly, it behaves differently: if it comes from the mother the girl is likely to be rather socially disruptive (the way little boys typically are), whereas if the X-chromosome comes from the father her behavior tends to be closer to normal for that of a girl!