Below is a list of terms, and their meanings, that are commonly used in egg donation. If you think that there are any missing definitions or an explanation of fertility treatment that you would like to see here, please contact us.

Altruistic – acting for the benefit of others

Anti-Müllerian Hormone (AMH) – is produced by cells in the ovarian follicles. Since AMH is produced only in small ovarian follicles, blood levels of this substance are thought to reflect the size of the remaining egg supply or ‘ovarian reserve’.

Antral Follicle Count (AFC) – an antral follicle is a later stage follicle. The antral follicle count is the total number of these follicles in the ovaries and gives a measure of the ovarian reserve.

Anonymous – the state of an individual’s personally identifiable information being publicly unknown.

Assisted Hatching – Technique involving the artificial creation of an opening in the outer covering of the zona pellucida of the embryo. Used to help the normal growing embryo to emerge from the covering in order to implant properly in the uterus. Can be done by use of lasers, chemicals or mechanically.

Blastocyst – a structure of cells formed in the early stages of embryo formation, beginning at day 5 after fertilisation. It possesses an inner cell mass which subsequently forms the embryo, and an outer layer of cells which later forms the placenta.

Blastocyst Transfer – This is performed when the embryos are cultivated for 4-5 days to approximately 64-cell stage at embryo transfer.

Blighted Ovum – A fertilised ovum that fails to develop into an embryo and usually results in an early miscarriage.

Body Mass Index (BMI) – is a measure of body fat based on height and weight that applies to adult men and women. BMI is a measure of whether you are a healthy weight for your height.

Buserelin – Buserelin (sometimes under the name of Suprecur) is a synthetic form of a naturally occurring hormone called Gonadotrophin-Releasing Hormone or GnRH. In egg donation it is used to stimulate the final maturation of eggs in the ovaries of egg donors. The eggs will be collected 36 to 40 hours afterwards.

Cervix – the cervix is the neck of the womb – the lower, narrow portion of the uterus where it joins with the top end of the vagina.

Cetrotide – This is one of the drugs used in egg donation. Cetrotide injections contain the active ingredient Cetrorelix, which is a synthetic form of a natural hormone called Gonadotrophin Releasing Hormone (GnRH).

Chromosomes – Structures within every cell that carry the hereditary material DNA.

Cleavage – The division of a fertilised cell into two new cells. Usually about 26 hours after fertilisation occurs.

Compensation – the making good of any losses incurred.

Conception – The joining together of the egg and sperm through to implantation.

Congenital – A characteristic or defect present at birth.

Corpus Luteum – The corpus luteum, which means yellow body in Latin, is what is left of the follicle after a woman ovulates. The corpus luteum produces progesterone, which makes the lining of the uterus thick for implantation.

Counselling – Counselling gives support from a trained professional who understands what is involved in treatment and offers the time to talk over options or concerns.

Cryopreservation – Preserving substances at very low temperatures in liquid nitrogen at –196 degrees centigrade, e.g. frozen sperm, embryos or eggs.

Cytomegalovirus (CMV) – A virus, which can cause severe disease in unborn babies if their mother catches the infection during pregnancy. Infection is common and by childbearing age 60-80% of the population will have been exposed to the virus. Catching the virus during pregnancy is not common.

Deoxyribonucleic Acid (DNA) – The basic biological hereditary molecules, which control many cell functions.

Donor Insemination – Artificial insemination using donated sperm.

Egg – the female reproductive cell, also called an ovum

Egg Collection or Recovery (EC) – Part of an assisted conception technique procedure. The eggs are aspirated from the stimulated ovary by laparoscopy or ultrasound – abdominally or vaginally

Egg Donation – a procedure in which a woman donates her eggs to another. It is typically used for an infertile patient who cannot produce her own eggs, her egg quality is poor or when the woman is the carrier of a genetic abnormality.

Egg Donor – a woman who is prepared to donate some of her eggs to another.

Egg Recipient – a woman who receives eggs donated by another woman.

Egg Sharing – A procedure where a patient needs to undergo IVF treatment and is willing to donate, usually half of her eggs harvested during a cycle of treatment to another patient. The recipient would normally cover the cost.

Embryo – the early stages of development of a baby. In humans, it is called an embryo until about eight weeks after fertilisation, and from then it is called a foetus.

Embryo Transfer (ET) – part of an assisted conception procedure when fertilised eggs are transferred into the uterus.

Endometrium – The lining of the womb.

Endoscopy – The visualisation of the interior of the body using instruments such as a laparoscope (abdominal cavity) and hysteroscope (uterus).

Fallopian Tubes – A pair of small, fine, delicate tubes between the ovary and the uterus (womb) where fertilisation usually takes place. The tubes transport and nourish the egg and sperm.

Fecundity – is the potential reproductive capacity of an individual, which is influenced by gamete production, fertilisation and carrying a pregnancy to term.

Fertilisation – The penetration of an egg by a sperm, also called conception.

Fertility – is the natural capability of producing children. Fertility differs from fecundity, which is defined as the potential for reproduction, although the term fertility is usually used to cover both meanings.

Foetus (US – Fetus) – Middle stage of development between an embryo and baby, when all main recognisable features are shown i.e. from the end of the second month of pregnancy.

Follicle – Circular fluid filled cavity within the ovary containing a developing egg.

Follicle Stimulating Hormone (FSH) – A hormone produced by the pituitary gland in the brain. In women it stimulates ovulation and the production of oestrogen. In men it stimulates the production of sperm.

Gametes – Female and male reproductive cells – egg (ovum) and sperm.

Genes – Parts of the chromosomes that control the inheritance of hereditary characteristics e.g. hair and eye colour.

Genetic – concerned with hereditary characteristics.

Genome – All the genetic material within the cells of an individual.

Gonads – The sex glands that make sex cells. These are the ovaries in the female and the testes in the male.

Gonal-F – This is one of the drugs used in egg donation (and the treatment of infertility) and directly affects the ovaries in women. The injection contains the active ingredient follitropin alfa, which is a synthetic version of a natural sex hormone called Follicle Stimulating Hormone (FSH).

Gynaecologist – A doctor who specialises in the investigation and treatment of the female reproductive organs and functions.

Hormone – A natural occurring chemical produced by the endocrine glands in the body, that circulate in the bloodstream to give an effect on a distant organ or organs, e.g. oestrogen produced by the ovaries and testosterone produced by the testes.

Human Fertilisation and Embryology Authority (HFEA) – the UK’s independent regulator overseeing the use of gametes and embryos in fertility treatment and research. It licenses fertility clinics and centres carrying out in vitro fertilisation (IVF), other assisted conception procedures and human embryo research.

Hyperstimulation – This is an excessive response of the ovaries to ovarian stimulation.

Hysteroscopy – The use of a very fine telescope to view the inside of the uterus via the cervix.

Implantation – The embedding of a fertilised ovum in the endometrium of the uterus.

Incubator – a device used to grow and develop fertilised eggs and embryos by maintaining optimal temperature, humidity and other conditions.

Infertility – Failure to conceive after regular unprotected sexual intercourse.

In Vitro Fertilisation (IVF) – A procedure whereby an egg or eggs are recovered by laparoscopy or vaginal ultrasound aspiration. This can be a natural or stimulated cycle, when drugs are used to make the ovaries produce more eggs. They are then placed with a specially prepared sperm sample – partners or donors – so that fertilisation can take place. The embryo(s) is/are then transferred to the uterus when it/they may implant and develop.

Laparoscopy – A technique in which the internal abdominal organs can be visualised directly, by using an instrument, which is introduced through a small incision in the abdominal wall below the navel.

Licensed Treatment Centre – a hospital, clinic or unit that is licensed by the HFEA to provide fertility treatments.

Luteinising Hormone (LH) – A hormone, which stimulates ovulation to take place.

Menopause – The cessation of menstruation usually occurring around the age of 50 years. The menopause is said to be premature when it occurs in a woman under the age of 35 years.

Menstruation – “The period”. The endometrium is shed if an embryo does not implant and produce a pregnancy.

Miscarriage – The loss of a pregnancy before the foetus is 24 weeks old.

Mitochondrion (pl. mitochondria) – Small structures (organelles) within a cell that are the principal source of energy for that cell, as well as performing a number of other important functions.

Oestrogen (US – Estrogen) – The female sex hormone produced by the ovaries.

Ovarian Hyperstimulation Syndrome (OHSS) – is a complication occasionally seen in women who take certain fertility medicines that stimulate egg production.

Ovarian Reserve – the capacity of the ovary to provide eggs that are capable of fertilisation resulting in a healthy and successful pregnancy.

Ovary (pl. ovaries) – The female reproductive organ(s) that contain eggs (ova), which produce the female hormones oestrogen and progesterone.

Ovitrelle – Ovitrelle injections contain the active ingredient Choriogonadotropin alfa, which is a synthetic version of a natural sex hormone called Human Chorionic Gonadotropin (HCG). In egg donation The Ovitrelle injection stimulates the final maturation of eggs in the ovaries of egg donors. The eggs will be collected 36 to 40 hours later for fertilisation in a laboratory.

Ovulation – The release of a mature egg from an ovarian follicle. This is usually around 14 days before the onset of menstruation.

Ovum (pl. ova) – the female sex cell or egg

Pituitary Gland – An endocrine gland at the base of the brain that produces several hormones including Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH). It is the master gland of the endocrine system of the body.

Polycystic Ovarian Syndrome (PCOS) – A condition where multiple cysts appear in the ovary. Abnormal hormone imbalance can arise causing problems with ovulation. It is diagnosed by blood test, vaginal ultrasound and signs such as increase in body weight, excessive hair growth and acne. These signs do not always manifest themselves in PCOS.

Pregnancy – is the fertilisation and development of one or more offspring, known as an embryo or foetus, in a woman’s uterus.

Pre-implantation Genetic Diagnosis (PGD) – A technique in which embryos are tested for specific genetic disorders before being replaced into the womb.

Progesterone – A hormone produced by the Corpus Luteum – where the egg leaves the ovary – after ovulation has occurred. The placenta also produces it in pregnancy.

Semen – The fluid ejaculated from the penis at orgasm containing sperm.

Spermatozoon – the male sex cell or sperm

Sperm Viability – Refers to whether or not the sperm are alive.

Stimulated Cycle – This is when drugs are given to the female in order for the ovaries to produce more eggs.

Superovulation – The use of fertility drugs to produce multiple follicles on the ovaries.

Surrogacy – The process involving a woman carrying s baby for another person (surrogate). In Host surrogacy, an IVF procedure is used so that the surrogate carries a child that is not genetically related to her. Part surrogacy involves the surrogate being inseminated with the man’s semen from the commissioning couple.

Testes (or testicles) – The male reproductive organs producing testosterone and sperm.

Testosterone – The male sex hormone produced in the testes or testicles.

Ultrasound Aspiration – A method used instead of laparoscopy to recover eggs from the ovary. The ultrasound image is achieved by abdominal or vaginal scanning and the eggs retrieved by needle aspiration from either of these two routes.

Ultrasound Scanning – High frequency soundwaves are beamed into the pelvis and, as they bounce back, are used to build up a picture. This can be performed abdominally (external) or via the vagina (internal). Organs such as the uterus and ovaries can then be visualised.

Uterus – A small, hollow, muscular organ found in the female pelvis that carries the fertilised ovum through the nine months of pregnancy, enlarging to accommodate as it grows.

Vagina – Front passage or birth canal. The tube that leads from a woman’s cervix to the outside (vulva).

Womb – a common name for the uterus

Zonal Drilling – The use of a chemical agent or a laser beam to dissolve part of the zona pellucida – egg coating – to help the embryo hatch out of the egg so that it can implant into the endometrium.

Zona Pellucida – The outside covering (shell) of a human egg.

Zygote – A fertilised egg.