Abortion: is the premature exit of the products of conception (the fetus, fetal membranes, and placenta) from the uterus. It is the loss of a pregnancy and does not refer to why that pregnancy was lost. A spontaneous abortion is the same as a miscarriage.

Amniocentesis: a procedure during which a small amount of amniotic fluid is aspirated with a needle from the amniotic sac under sonographic guidance. It usually takes place between 16 and 20 weeks of pregnancy. The amniotic fluid that contains exfoliated skin cells from the fetus is sent for Karyotype and genetic analysis in order to test for chromosomal abnormalities (e.g. Trisomy 21) or other genetic syndromes.

Amnion: the membrane comprising the inner layer of the wall of the pregnant uterus which forms the amniotic sac, wherein the embryo grows.

Amniotic fluid: the fluid contained in the amniotic sac.

Ampoules: small glass vials containing pharmaceutical substances like fertility medications

ART (Assisted Reproduction Technologies): any artificial technique that helps women conceive, most people mainly refer to IVF and ICSI.

Assisted Hatching: the artificial breaching of the outer layer (Zona Pellucida) of an embryo by mechanical (e.g. Laser) or chemical means in order for it to expand (“hatch”) and implant in the womb.

Azoospermia: the complete absence of motile (alive) spermatozoa in the ejaculatory fluid.


Blastocyst: the embryo that has developed for 5-6 days after fertilization. It has a small fluid containing cavity.

Blastomere: are the cells that are produced by cell division of the fertilized egg. They are usually taken by biopsy of a blastocyst of PGD or PGS.


Cell: the smallest structural and functional unit of an organism, which is typically microscopic. Complex organisms, like humans, are comprised of differentiated somatic and genetic cells.

Cervical Mucus: high viscosity fluid (gel like) that is produced in the cervical canal. The amount and nature of the mucus changes around the time of ovulation in order to allow the spermatozoa through the cervix into the uterine cavity.

Cervix: the lowest part of the uterus. It contains the passage that connects the uterus with the vagina. It is dense in nature and keeps the fetus in the uterus during pregnancy.

Chlamydia: a sexually transmitted disease that can cause serious problems in the female and male reproductive system, resulting in infertility. They can be asymptomatic. In the females they can cause blockade of the salpinges and other problems.

Chorion: the outer layer of the early placenta.

Chromosome: a thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. In humans there are 23 pairs of chromosomes (i.e. 46 chromosomes) and they carry all the genetic information from parents to their offspring.

Clomiphene citrate: a fertility drug taken by mouth that induces the production of more endogenous FSH, which in turn stimulates the ovaries, resulting in the production of more than one follicle in a cycle.

Cloning:  the production of two or more genetically identical individuals.

CMV (Cytomegalovirus):  a virus that can cause flu symptoms (fever, sore throat, malaise) but usually is asymptomatic. The largest percentage of adults have been exposed to the virus and are immune. During pregnancy it can cause problems to the fetus.

Congenital anomalies:  any anomaly that is present at birth and is a result of inherited or acquired causes.

Corpus Luteum:  the structure that forms after the rupture of the follicle (ovulation) and produces progesterone. The main function is to prepare the endometrium, making it more receptive to an embryo and later on to support the progress of the pregnancy. If pregnancy does not occur, it degenerates within a few days.

Cryopreservation:  the method of preserving gametes or embryos via freezing in very low temperatures.

CVS (Chorionic Villi Sampling):  the technique during which a small sample of chorionic villi (part of the early placenta) is aspirated by a needle under sonographic guidance. The sample is sent for genetic analysis of the embryo. It usually takes place between 11 and 13 weeks of pregnancy.

Cytoplasm:  the gelatinous material that fills the cell around the nucleus.



Ectopic pregnancy:  a pregnancy that occurs outside the normal environment, the endometrial cavity. It usually occurs in the tubes, but can occur in the ovaries and other places within the abdomen.

Embryo culture:  the development of embryos outside the human body in a laboratory environment.

Embryo Reduction:  sometimes it is necessary to reduce the number of embryos that grow inside the uterus. This usually takes place in order to protect the health of the mother or in order to give a better chance to the remaining embryo for intact survival. The less the embryos transferred in an IVF cycle the less the need for embryo reduction.

Embryo Transfer: the transfer of one or more embryos in the uterus.

Embryo: the fertilized oocyte that has the potential to develop in a complete living organism.

Endometriosis:  the condition where endometrial tissue (which normally exists in the uterus) grows in areas outside the uterus. It can cause cyclical pain, ovarian cysts and infertility.

Endometrium:  the inner lining of the uterine cavity, that grows in thickness in every cycle and gets discarded as menses if pregnancy does not occur.

Epididymis: it is a long (approx.7m) convoluted thin tube in the posterior surface of the testicle that connects it to the spermatic cord. The spermatozoa are stored in the lower part until ejaculation takes place.

Estrogens:  steroid hormones which promote the development and maintenance of female characteristics of the body. The main representative is Estradiol during the reproductive ages of a woman.


Follicle:  a fluid filled sac that contains the oocyte and grows every month in the ovary until ovulation, when it ruptures.

Fresh and frozen cycle:   in most cases the collected oocytes from the female are fertilized by the spermatozoa of the male partner with the In Vitro Fertilization method, thus creating embryos. If the embryos are transferred a few days later (fresh) in the uterus then this cycle is called “fresh”. If the embryos are not transferred immediately or if there is a surplus of embryos after the fresh cycle then these embryos are cryopreserved. When the embryos are thawed and transferred in the uterus, then this cycle is called “frozen”.

FSH (Follicle stimulating hormone): the hormone that is produced by the hypophysis and stimulates the growth of follicles in the ovary.

Fundus of uterus: the upper part of the uterus, like a dome.


Gamete: in men it is the spermatozoon and in women the oocyte. When they combine in fertilization it is called Zygote.

Gene:  the inherited unit that contains a specific genetic information. It is comprised from a cascade of DNA bases. Every person inherits 2 copies of each gene.

Genome: genome is an organism’s complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism.

GIFT (Gamete Intra Fallopian Transfer):  the procedure during which the oocytes that are collected are mixed with spermatozoa and placed directly in the salpinx of the female where the fertilization takes place (in vivo).

GnRH (Gonadotropin Releasing Hormone):  the hormone that is produced by the hypothalamus periodically (in waves) and stimulates the production of gonadotropins form hypophysis.

Gonadotrophins:  the hormones that are produced by the hypophysis (FSH, LH) and are responsible for the production, growth and ovulation of the follicles.


HCG (Human Chorionic Gonadotropin):  the hormone that we measure at the pregnancy test. It is produced by the chorionic villi of the placenta

Hemoglobin Electrophoresis: a laboratory method to identify hemoglobin diseases, like α and β thalassemias.

HMG (Human Menopausal Gonadotropin):  a fertility drug that contains various mixtures of FSH and LH, it is derived from urine of menopausal women and purified.

Hyperstimulation syndrome of the ovaries (OHSS):  an over response of the ovaries that produce many follicles during stimulation with fertility drugs. This results in increased size of the ovaries and can cause symptoms like pain, swelling, nausea and more.

Hypophysis:  it is an endocrine gland of the brain that is located on the base of the skull, bellow a region of the brain called hypothalamus. It produces among other hormones FSH and LH.

Hypothalamus: the region of the brain that lies bellow the thalamus as the word implies and one of its major function is to control the secretion of the hormones of the hypophysis.

Hysterectomy:  the surgical removal of the uterus.

Hysterosalpingography: the procedure where X-rays are taken of a woman’s reproductive tract after a dye is injected. Hystero means uterus and salpinges means tubes, so hysterosalpingography literally means to take pictures of the uterus and fallopian tubes. This way we can see the shape of the uterine cavity and the patency of the tubes.


ICSI (Intra Cytoplasmic Sperm Injection):  the injection of a single sperm cell in the cytoplasm of an oocyte with a microscopic needle in order to fertilize the oocyte.

Implantation:   the procedure during which the embryo is implanted (adhered) in the endometrium.

In vitro:   a procedure that takes place outside the body, usually in the laboratory.

In vivo:  a procedure that takes place inside the body.

Incomplete cycle: the cycle in an IVF trial that gets cancelled after the initiation of stimulation drugs but before the oocyte retrieval.

Inner cell mass:  it is the cell mass that grows on one side inside a blastocyst, and from which the embryo develops.

IUI (Intra Uterine Insemination):  a fertility treatment that involves placing sperm inside a woman’s uterus to facilitate fertilization. The goal of IUI is to increase the number of sperm that reach the fallopian tubes and subsequently increase the chance of fertilization.

IVF (In Vitro Fertilization):  the fertilization of an oocyte by a sperm cell outside the human body, in laboratory conditions. The embryos created by this procedure can then be transferred inside the uterus.



Karyotype:  the microscopic appearance of all the chromosomes of a cell, including their number, shape, and size.


Laparoscopy:  a type of surgery in which small incisions are made in the abdominal wall through which a laparoscope and other instruments can be placed to permit structures within the abdomen and pelvis to be seen. A variety of probes or other instruments can also be pushed through these small incisions in the skin.

LH (Luteinizing Hormone):  the hormone produced by hypophysis that regulates the growth and ovulation of the oocyte, and the corpus luteum which supports the pregnancy.

Live Birth Rate: the number of live births resulting after 100 cycles of IVF.


Menstrual cycle:  refers to the cycle that occurs in women approximately every month. During this cycle an oocyte is produced and the endometrium thickens in order to prepare for the possible implantation of the fertilized oocyte. If pregnancy does not occur the endometrium sheds off as menstrual flow.

MESA (Microsurgical Epididymal Sperm Aspiration):  the aspiration of sperm cells from the testicle using microsurgical techniques.

Mitochondria:  it is an organelle that exists inside the human cells and are responsible for most of the energy requirements of the cell. They contain small amounts of mitochondrial DNA that is inherited from the mother and not from the father.

Monozygotic Twins: the twin embryos that derive from a single oocyte. It happens when a fertilized oocyte is divided at some point to two different zygotes.

Morbidity:  the rate of a disease in a population.

Mortality: the relative incidence of death within a particular group categorized according to age or some other factor such as occupation.

Morula: a solid ball of cells resulting from division of a fertilized ovum, and from which a blastula is formed.

Multiple Pregnancy:  a pregnancy during which more than one embryo develops in the uterus. (e.g. Twins, Triplets)

Myoma (fibroid):  a benign mass of muscle and fibrous tissue that develops in or around the uterus. It can cause pain, heavier menses or even infertility depending on the size and location but it is usually asymptomatic.


Natural Cycle: it usually refers to the unstimulated cycle of a woman where a single oocyte is produced.

Neonatal Death:  a death during the first 28 days of life.

Nucleus:  the central organelle of a cell, spherically shaped, that contains the genetic material (DNA).


OHSS (Ovarian HyperStimulation Syndrome): an over response of the ovaries resulting in the production of many follicles during stimulation with fertility drugs. This results in increased size of the ovaries and can cause symptoms like pain, swelling, nausea and more.

Oligozoospermia:  the low number of spermatozoa per ml (< 15 million spermatozoa/ ml according to WHO.

Oocyte donation:  the procedure during which a fertile woman, usually of younger age, donates her oocytes  to another women that has low number or quality of oocytes or no oocytes at all. The donor undergoes controlled ovarian stimulation and oocyte retrieval, then In Vitro Fertilization with the spermatozoa takes place and the resulting embryos are placed in the recipient uterus.

Oocyte Retrieval:  the procedure during which the oocytes are retrieved from the ovaries. A needle is inserted trans-vaginally under sonographic guidance for the aspiration of the follicular fluid that contains the oocyte. Sedation is usually given.

Oocyte:  the gamete that is produced in each cycle from a woman’s ovaries.

Ovaries:  the female gonads. They are 2 in number.

Ovulation Trigger:  the signal that prompts ovulation. In natural cycle the signal is given by LH, in stimulation cycles an injection of HCG is given that mimics the action of LH. Ovulation usually happens 32-36 hours after the trigger.

Ovulation: the rupture of the follicle and the release of an oocyte from the ovary.


PCOS (Poly Cystic Ovarian Syndrome):   a common syndrome among women of reproductive age. The ovaries have a characteristic sonographic appearance with many peripheral small follicles (misnamed as “cysts”) which is combined with menstrual irregularities due to anovulation and signs of hyperadrogenism (like Acne and Hirsutism)

PCR (Polymerase Chain Reaction): is a laboratory technique used to make multiple copies of a segment of DNA. PCR is very precise and can be used to amplify, or copy, a specific DNA target from a mixture of DNA molecules.

Perinatal Mortality: the rate of death among embryos after the 22nd week of pregnancy and neonates up to 1 week after birth.

Peritoneal Cavity:  the cavity within the abdomen that contains most gastrointestinal organs as well as the uterus and salpinges, it is covered by a thin layer of tissue called the peritoneum.

PESA (Percutaneous Epididymal Sperm Aspiration):  the technique of sperm collection during which a thin needle is passed through the skin of the scrotum and aspirates the spermatic fluid from the area of epididymis. This takes place under local or general anesthesia.

PGD (Pre-implantation Genetic Diagnosis):  the removal of one or more cells from the developing embryo in the laboratory during an IVF cycle in order to be genetically tested for specific inherited diseases or characteristics before an embryo transfer.

PGS (Pre-implantation Genetic Screening):  the removal of one or more cells from a developing embryo in the laboratory during an IVF cycle in order to identify if they contain the correct number of chromosomes (i.e. eukaryotic)

Polyp: a small growth, usually benign and with a stalk, protruding from a mucous membrane. In gynecology a polyp usually grows from the endometrium or the cervix.

Pregnancy rate:  the number of pregnancies achieved in 100 cycles of IVF.

Progesterone:  it is the major hormone that promotes gestation (pregnancy). It is produced by the corpus luteum initially to make the endometrium more receptive to the embryo and later on by the placenta to promote the pregnancy.

Pronuclear: the nucleus of the spermatozoon and the oocyte at the stage of initial fertilization after the sperm enters the ovum, but before they fuse. Sperm and egg cells are haploid, meaning they carry half the number of chromosomes.

Prostate:  the gland that produces the alkali fluid (high pH) of sperm.




Salpinx:  a thin elongated, freely moving tube that connects the endometrial cavity with abdominal cavity.  They are approx. 10cm long and contain ciliated cells that promote the transfer of spermatozoa towards the ovary and subsequently the transfer of the oocyte and embryo in the opposite direction towards the uterus. Their function is necessary for natural fertilization.

Sex selection:  when the sex of an embryo is selected by PGS and subsequently transferred in the uterus in order to avoid sex linked disorders.

Single IUP (Intra Uterine Pregnancy):  the gestation of only one embryo in the uterus.

Spermatozoa:  the mature male gamete, consisting of a flattened egg-shaped head, a long neck, and a whip like tail by which it moves to fertilize the female ovum. It is produced by the testicle and usually takes approx. 74 days for the procedure (spermatogenesis).

Spindle: The mitotic spindle is a group of spindle fibers that divide chromosomes during mitosis. The spindle helps to split the chromosomes from a parental cell into two daughter cells.

Stem cells:  an undifferentiated cell that has the capability to differentiate (transform) into other kind of cells in the body (e.g. skin, blood cells) and can produce an indefinite number of cells of the same kind.

Stimulated cycle: a cycle in assisted reproduction during which ovaries are stimulated with medications in order to produce more than one oocyte.

Storage of Embryos:  the procedure during which the embryos are cryopreserved (freezed) in order to be preserved for the future.

Surrogate mother:  the procedure during which a woman carries the embryo on behalf of another person.

SUZI (Sub zonal sperm injection):  the procedure during which one or more spermatozoa are injected in the zona pellucida (the outer zone) of an oocyte.


Teratozoospermia:  the presence of more than expected malformed spermatozoa that affects male fertility.

TESA (Testicular Sperm Aspiration):  the aspiration of spermatozoa with a needle from the testis.

TESE (Testicular Sperm Extraction):  the technique of extracting spermatozoa from a small biopsy specimen from a testis.

Testis:  or testicle, is the pair of male gonad that is located in the scrotum. It is responsible for production of sperm and male steroid hormones.

Trisomy:  it occurs when instead of a pair of chromosomes, which is the normal, there is a third extra one.  The most well-known Trisomy is at the chromosome 21 pair, also known as Trisomy 21 or Down syndrome.


Ultrasound:  a beam of high frequency sound waves that are used to create an image of tissues, internal organs and the fetus. It is considered harmless.

Uterus:  A hollow muscular organ consisting of a body, fundus, isthmus, and cervix located in the lower abdomen, pelvic cavity of female mammals, in which the fertilized egg implants and develops into the fetus. Also called metra, womb.


Varicocele: the tortuous enlargement of the venous system of the testicle, creating varicose veins in the scrotum.

Vitrification:  a new method of cryopreserving gametes (e.g. oocytes) and embryos without creating ice crystals. This is achieved by fast freezing to temperatures as low as – 196 C degrees in a medium that contains high concentration of cryoprotectants.





ZIFT (Zygote Intra Fallopian Transfer):  the transfer of a fertilized oocyte in the salpinges laparoscopically.

Zygote:  the cell that is produced as a result of fertilization of the 2 gametes.