Glossary of terms


The gain or loss of one or more chromosomes at meiosis, including trisomy (47 chromosomes) and monosomy (45 chromosomes). Caused by chromosomal nondisjunction.

anti Müllerian hormone (AMH)

This is a protein released by the ovaries and is related to the development of follicles in the ovary. 

assisted conception

A group of medical treatments ranging from assisted insemination (AI) to in vitro fertilisation (IVF), including its technical variants or components such as intracytoplasmic sperm injection (ICSI) and pre-implantation genetic testing or diagnosis (PGD).

Assisted conception techniques have the following common characteristics: (1) they are aimed at increasing the chance of pregnancy each month, thus overcoming the medical disability of infertility; (2) there is little or no “spillover” of therapeutic effect beyond the cycle or month in which treatment is invoked; and (3) there is some form of procedural intervention, with sperm, eggs or embryos spending some time outside of the body. It’s not necessary for there to be stimulation of the ovaries (superovulation) for multiple development of follicles.

assisted insemination (AI)

Insemination, or injection of semen or prepared spermatozoa, into the vagina, cervix, uterus (intrauterine insemination) or fallopian tube, to treat infertility. A basic form of assisted conception. The male partner’s sperm (AIH) or donated sperm (DI) can be used. 


Taking a small sample of tissue for diagnosis.


An embryo whose cells have divided into 2 different types (placental and fetal) and which surround a central, fluid-filled cavity (usually forms 5-6 days after fertilisation).

Secretions produced by the cervix that, at the time of ovulation, assist the passage of sperm through the cervix.

Secretions produced by the cervix that, at the time of ovulation, assist the passage of sperm through the cervix.


The “neck” of the uterus, lying between the body of the uterus (its fundus) and the vagina.


A GnRH antagonist made by Merck Serono.


Process by which a fertilised egg divides repeatedly over several days, forming (for a time) smaller and smaller cells; the process begins at the stage of the zygote and ends with a morula. 


Synthetic ovulation stimulant made by Sanofi-Aventis.

comparative genome hybridisation (CGH)

A powerful technique using molecular tools that allows accounting for all 23 pairs of chromosomes and the sex chromosomes, with high accuracy. CGH is used for pre-implantation genetic screening (PGS) in order to avoid abnormal pregnancies and/or miscarriages.


The act of becoming pregnant. Traditionally, the fertilisation of the egg (the oocyte) by a sperm (the spermatozoon) and the beginning of the growth of the embryo [Butterworths Medical Dictionary]. Since the advent of in vitro fertilisation, conception is said to have occurred only if the conceptus has undergone successful implantation, as evidenced by a positive pregnancy test.

corpus luteum

This very important structure mainly produces progesterone, the hormone necessary for transforming the endometrium so that a fertilised egg (the early embryo) can implant and develop. 

Crinone ®

Vaginal cream containing natural progesterone made by Merck Serono.


Storage (at the very low temperature of liquid nitrogen) of sperm, embryos or unfertilised eggs, after special preparation of these cells during cooling to replace much of the water they contain with a cryoprotective substance.

culture medium

The fluid in which cells or tissues, including eggs, sperm and embryos, are grown. It consists of water, salts and nutrients. Plural: culture media.

cumulus mass

A collection of specialised granulosa cells, surrounding the ovulating egg (or secondary oocyte) in a sticky, mucus-like matrix. Sticks to the fallopian tube’s fimbrial end after ovulation by a specific interaction with the tube’s cilia.


The stuff of which genes are made. DNA is an abbreviation of deoxyribonucleic acid, a molecule made of a variable sequence of units, the nature and order of which forms the genetic code. DNA is located chiefly in the chromosomes, which form a cell’s nucleus. 


General term for oocyte.

egg collection (also known as egg retrieval, ovum pick-up, or transvaginal oocyte aspiration (TVOA)

Procedure for obtaining eggs (oocytes), involving the passing of a needle into a mature (or preovulatory follicle, either directly at laparoscopy or (more usually) via the vagina guided by transvaginal ultrasound.


The word is used loosely to describe everything from a fertilised egg (or zygote) to a fetus, including the embryo. What nowadays we call the embryo has for long been called the ovum by professional embryologists. 

embryo biopsy

A biopsy, or removal of up to six cells, from an early IVF embryo for pre-implantation genetic diagnosis after in vitro fertilisation.

embryo transfer (ET)

Procedure by which the embryo is placed in the uterus after in vitro fertilisation.


A common condition in which tissue like the lining of the uterus (the endometrium), grows somewhere else, sometimes causing painful periods, premenstrual spotting, infertility, painful intercourse and ovulatory dysfunctional uterine bleeding.


The lining of the uterus, which contains the endometrial glands and the endometrial stroma. Distinct from the myometrium.


Estrogen develops the watery mid-cycle changes in cervical mucus that assist the passage of sperm into the uterus and also causes the thickening of the endometrium required for implantation. Also spelt oestrogen.

fallopian tube

A pair of narrow tubes that carry the egg from the ovary to the body of the uterus in which fertilisation occurs.


Penetration of the egg by a sperm cell which results in combining of genetic material.


An unborn baby. The product of conception from the time the embryo is fully formed (from head to limbs – about 8 weeks from the last menstrual period) until delivery. Also spelt foetus.

fluorescent in situ hybridisation

Known as “FISH”. A form of DNA testing for genetic diagnosis in which a special region of a chromosome is stained with a dye that emits colored light when exposed to ultraviolet light. For example, a marker for chromosome 21 will normally show two spots of light, whereas three spots of light would indicate trisomy 21 (Down syndrome).


A small fluid-filled cyst on the ovary in which the eggs grow until released and which produces estrogen.

follicle stimulating hormone (FSH)

The hormone produced by the pituitary gland which controls growth of ovarian follicles and maturation of egg cells in a woman and sperm production in a man.

follicle tracking

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 luteinising hormone (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 collection) and identifying the onset of the LH surge, which can affect the timing of the intervention.

Follicular phase

The part of the ovary’s monthly cycle before ovulation.


The smallest unit of inheritance coded by DNA. Generally, a single gene codes for a single protein. Genes come in pairs of alleles (one inherited from each parent) in all tissues except the haploid cells, particularly the spermatozoon.

genes and chromosomes

Our entire DNA is formed by about 25,000 genes, containing our genetic information and ordered in a specific pattern. The entire DNA is arranged in bigger structures called chromosomes, containing all the genes (all the genetic information of our species).


Genea's GeneSure™ PGD analysis is a valuable tool in helping genetically identify the best embryo to boost your chance of a genetically normal pregnancy.


First Trimester Biochemical Screening, through Genea, measures three hormones in the mother’s blood between the 10th and 14th week of pregnancy to screen the pregnancy for the risk of Down syndrome and pre-eclampsia.

GnRH agonist

A group of drugs that cause a flare followed by a drop in follicle stimulating hormone (FSH) and luteinising hormone (LH) as they stimulate and then inhibit, or down regulate, the pituitary gland. There are two agonists available in Australia – a nasal spray called Synarel® (Pfizer) and an injection called Lucrin® (Abbott).

GnRH analog

A group of drugs closely related to the natural hormone gonadotrophin releasing hormone (GnRH), a hormone produced by the hypothalamus in the brain that controls the release of follicle stimulating hormone (FSH) and luteinising hormone (LH) by the pituitary gland. There are two types of analogs – agonists and antagonists – that prevent an LH surge in different ways.

GnRH antagonist

A newer class of injectable medication with the advantage that levels of follicle stimulating hormone (FSH) and luteinising hormone (LH) are reduced without first causing the flare, meaning they are given for a much shorter period of time. They are usually started on the sixth day of FSH stimulation.


One of the drugs used to stimulate the development of follicles. Recombinant follicle stimulating hormone (FSH) made by Merck Serono.


A chemical substance, natural or not, which acts as a signal from one part of the body to another, via the bloodstream. The study of hormones is the science of endocrinology, and the hormone systems of the body are collectively known as the endocrine system.

human chorionic gonadotropin (hCG)

A hormone that tells the corpus luteum to continue progesterone production.

hysterosalpingogram (HSG)

This is an x-ray to enable radiographs to be taken demonstrating uterine outline and the fallopian tubes.


The process by which the embryo’s trophoblast attaches to the mother’s endometrium and penetrates it. Signifies the commencement of gestation or pregnancy.

in vitro fertilisation

IVF, or fertilisation of the egg (the secondary oocyte) by a sperm (a spermatozoon) in vitro, i.e. in the laboratory.


The inability to conceive or carry a baby to term after 12 months of unprotected sex.

inner cell mass

Group of cells that differentiates within (but to one side of) the developing embryo when it is a blastocyst and which will, if all goes well after implantation, form the embryo-proper, or fetus. Cells from the inner cell mass can be used to produce embryonic stem cells.

intracytoplasmic sperm injection (ICSI)

An in vitro fertilisation technique for overcoming infertility due to severe male factor infertility involving sperm microinjection, in which one sperm is injected into the egg. 

intrauterine insemination (IUI)

A form of assisted conception involving assisted insemination into the uterus, either for donor insemination (DI) or with the partner’s semen (AIH). IUI can be carried out with a woman’s natural cycles or with ovarian stimulation (superovulation) using clomiphene or follicle stimulating hormone, with ovarian monitoring.

last menstrual period (LMP)

The normal period immediately preceding conception. For convenience, obstetricians calculate the duration of a pregnancy as starting with this date, even though of course it does not truly begin until fertilisation (or, some would say, implantation).

LH surge

An increase in luteinising hormone (LH) that triggers the final maturation of the egg, the rupture of the follicle, and then the release of the egg. This usually happens 14 days before the next period is due, or on day 14 of a 28-day cycle.


A GnRH agonist administered as an injection, made by Abbott.

luteal phase

The days of a menstrual cycle following ovulation up to menstruation.

luteinising hormone

A hormone produced by the pituitary gland which triggers ovulation.


Human follicle stimulating hormone and luteinising hormone made by Ferring.

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.


The delivery of (or the process of delivering) a conceptus before there is a viable fetus.


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.


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 fertilised egg, or zygote, by the processes of cleavage and compaction. 

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’s syndrome.


Central structure within a cell that contains the chromosomes.


The form of the ovum, or egg, which is undergoing a halving of the number of chromosomes through the process of meiosis.


Ovum pick-up or egg collection.


The GnRH antagonist made by Organon.

ovarian hyperstimulation syndrome (OHSS)

A complication of ovulation induction with, usually, follicle stimulating hormone (FSH), 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.


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).


Recombinant human chorionic gonadotrophin (hCG) used for trigger prior to egg collection, and made by Merck Serono.


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.

ovulation induction (OI)

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).

pituitary gland

Gland located at the base of the brain and responsible (among other jobs) for driving the ovaries in women and the testes in men by way of the pituitary hormones, follicle stimulating hormone (FSH) and luteinising hormone (LH), which are under the influence of gonadotropin releasing hormone (GnRH) from the hypothalamus.


That part of the products of conception apart from the fetus where blood from the fetus and from the mother come into intimate contact to exchange nutrients and waste. Composed of trophoblast. Together with the membranes (of the gestational sac) and the umbilical cord composes the ‘afterbirth’.

polycystic ovaries (PCO)

It’s a diagnosis best made on transvaginal ultrasound, with lots of medium-sized follicles visible around the rim of the ovaries.

polycystic ovary syndrome (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).


A benign growth of tissue, usually of the lining of a hollow organ such as the intestine or the uterus.


The state of being with child [British Medical Dictionary]; specifically, the condition from implantation of the conceptus until its delivery.


Human chorionic gonadotrophin (hCG), made by Organon and used for trigger prior to egg collection and sometimes for luteal support following egg collection.

pre-implantation genetic diagnosis (PGD) and polymerase chain reaction (PCR)

Traditionally, PGD accounts for all techniques that allow testing of the genetic characteristics of the embryo before it is transferred or put back in the mother’s uterus. The PGD technique of PCR allows testing for a specific genetic condition. PCR makes millions of copies of the gene, allowing scientists to analyse it and see if it is normal or has a mutation.


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.

Progynova® (oestradiol valerate) 2mg

Oral estrogen, made by Bayer.


A visible ‘blob’ inside a mature oocyte 18 hours after insemination. There are two of them in an egg that has undergone normal fertilisation or activation by other means. They enclose the chromosomes from the oocyte (the female pronucleus) and from the sperm (the male pronucleus).


The progestogen medroxyprogesterone acetate, made by Pfizer.


Recombinant follicle stimulating hormone made by Organon.

recurrent miscarriages

A series of three or more consecutive miscarriages.


Fluid produced by the male genital tract at ejaculation. Contains spermatozoa, as well as many other substances, including those that make the ejaculate coagulate (and then called a coagulum, which is given time to liquefy before a semen analysis is done on it). Sperm cells account for only about 1% of the volume of the ejaculate, so it’s not possible to be confident about a man’s sperm count just on the basis of the volume of the semen ejaculated.

semen analysis

Formal name for a sperm count which includes concentration, motility, morphology, ASABs and SCSA.

semen sperm antibodies (ASABs)

A test for detecting sperm antibodies in semen.


Synthetic ovulation stimulant manufactured by Merck Serono.

sperm antibodies

The result of a reaction of the immune system against sperm cells (spermatozoa) and, by limiting the ability of sperm to show motility, a contributory (or occasionally the only) cause of infertility. Can be present in serum, in cervical mucus or in semen.

sperm chromatin structure assay (SCSA)

A test, the purpose of which is to measure the amount of damaged sperm DNA in semen samples of male patients.

sperm count

A semen analysis measuring the volume of the ejaculate, the density of spermatozoa (sperm/sperm cells) in it (expressed as so many million sperm per millilitre), the proportion of sperm swimming normally (the motility), and the proportion with a normal shape.

sperm or sperm cells

Common abbreviation for spermatozoon (or for the plural form, spermatozoa). 

stimulated cycle

An in vitro fertilisation (IVF) cycle that uses a course of hormones to stimulate the ovaries with the aim of collecting more than one egg.


Infertility that is not absolute or complete (sterility) i.e. there is a possibility of pregnancy. However, the chance of getting pregnant each month (fecundability or monthly fertility) is reduced.


‘A person who acts for or takes the place of another’ [Oxford English Dictionary]. In reproductive medicine, a woman who has a baby on another woman’s behalf.


A GnRH antagonist administered as a nasal spray, made by Pfizer.

testicular biopsy

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

testicular sperm aspiration (TESA)

When sperm cannot be obtained from the semen in the ejaculate, sperm can be taken directly from the testis and used in the IVF programme. Men requiring this usually have some form of obstruction or a very low production of sperm cells.

A small piece of tissue containing the sperm may be drawn from the testis using a small needle. The procedure is undertaken in a suite within Hollywood Fertility Centre under local anaesthetic with oral sedation. Any remaining sperm may be frozen if suitable.

testicular sperm extraction (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 (IVF) using intracytoplasmic sperm insertion (ICSI).


The main male sex hormone, or androgen, in the blood.

trans-vaginal oocyte aspiration (TVOA)

Term meaning egg collection.


An imaging procedure like radar, but using high frequency sound waves.


The muscular organ where a fertilised egg, or embryo, attaches and develops. It is the size and shape of a pear and lined with a rich and nourishing membrane, the endometrium.

vas deferens

The long duct that transports sperm cells from the epididymis to the seminal vesicles.


Vitrification comes from the Latin word vitrium, meaning glass. In the context of freezing embryos, vitrification is the process whereby the solution containing the embryos is cooled so quickly that the structure of the water molecules doesn’t have time to form ice crystals and instantaneously solidifies into a glass-like structure.

zona pellucida

The tough but glassy-looking membrane that starts to surround the egg (the primary oocyte) while it’s still in the follicle, protects it against immature sperm at its surface, and keeps the cells of the early embryo together until the embryo, as a blastocyst, hatches through it in preparation for implantation.

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