Glossary

Amniocentesis: Transabdominal aspiration of fluid from the amnionic sac surrounding the developing fetus. Cells within the fluid are cultured in vitro and analyzed to detect genetic abnormalities in the fetus.

Assisted Hatching: The process in which a microscopic opening is made in the “shell” or zona pellucida to facilitate the embryo’s release or “hatching” from it’s shell. This microscopic hole can be produced by several methods: mechanical “microsurgery” to cut an opening in the zona or chemical dissolution of a small part of the zona using microscopic quantities of acid. Hatching is essential to permit implantation (and pregnancy) to occur and normally the expansion of the developing fetus is sufficient to breach the zona pellucida. However, in some older patients or patients with extremely thick zona pellucidas, assisted hatching has been shown to be beneficial in increasing pregnancy rates.

Assisted Reproductive Technology (ART): A term that refers to a group of technological laboratory and medical procedures that function to bypass or compensate for reproductive system failures or abnormalities to allow pregnancy to occur. Examples of ART procedures include artificial insemination, intrauterine insemination (IUI), in vitro fertilization (IVF), Gamete intrafallopian tube transfer (GIFT), zygote intrafallopian tube transfer (ZIFT), assisted hatching and intracytoplasmic sperm injection (ICSI).

Azoospermic: The absence of sperm cells in the ejaculate.

Blastocyst: the stage of development typically reached on the fifth day after fertilization in humans. The blastocyst consists of 50-100 cells that are organized into three structures, the inner cell mass, trophectoderm and blasotcoel cavity containing fluid. The cells of the inner cell mass will form the structures of the fetus. The trophectoderm will form the fetal part of the placenta. The blastocyst enlarges, in part by pumping fluids into the blastocoelic cavity, stretching and opening the zona pellucida so that it can “hatch” from the zona pellucida and implant in the uterus.

Chorionic villus sampling (CVS): Removal of a small sample of the chorionic villus via transabdominal aspiration. This procedure can be performed at an earlier stage of pregnancy than amniocentesis. The CVS sample is tested for chromosomal abnormalities.

Chlamydia: The bacterium Chlamydia trachomatis is responsible for many reproductively significant clinical syndromes including nongonoccocal urethritis (NGU) or epididymitis in men and mucopurulent cervicitis and pelvic inflammatory disease (PID) in women. These syndromes, if untreated can contribute to infertility in both men and women. Chlamydia trachomatis can be transmitted by sexual intercourse.

Cryobanking: The storage of supercooled living specimen (e.g. eggs, sperm, embryos, ovarian or testicular tissue) in liquid nitrogen to preserve function and integrity of the specimen for decades, if not indefinitely. Indiana State Law requires infectious disease testing of men who wish to donate semen for insemination. The American Society of Reproductive Medicine (ASRM) Guidelines recommend infectious disease testing of both male and female prior to any assisted reproductive techniques.

Cryopreservation: The preservation of the integrity and function of a cell, embryo or tissue by means of freezing the specimen to ultralow temperatures which do not support metabolic activity, resulting in a suspended animation state. Typically, the specimen to be frozen is immersed in a cryoprotectant solution that prevents ice crystal formation as the temperature is lowered to freezing. Ice crystal formation destroys the structural integrity of living materials and cryoprotectants typically consist of salts or other additives that can exclude water from the specimen before ice crystals are able to form.

Cumulus oophorous complex: The cumulus complex is a heap of epithelial cells that surround each egg within each growing follicle of the ovary. The cumulus cells function to nurture the egg and regulate its development in the follicle of the ovary. Receptors on the cumulus cells respond to the mid-cycle surge of hormones preceding ovulation and transmit the signals to initiate ovulation to the egg. The cumulus complex remains around the egg after ovulation and is normally present at fertilization. In many species, the cumulus complex is necessary for normal sperm activation enabling fertilization.

Cytomegalovirus (CMV): A group of viruses in the family Herpesviridae that produce characteristic inclusions in the cytoplasm or nucleus. Infection of the embryo in utero may result in malformation and fetal death. Virus can be transmitted by sexual intercourse. Diagnostic tests are available to detect the virus in blood.

Fallopian tube: Named after Gabriel Fallopio, the Italian anatomist, who identified this structure in human. This structure is also referred to as the “oviduct” or egg duct in animals. It is a multi-functional tube connecting the ovaries to the uterus. Specialized cells located at the fringed ends or fimbria of the oviduct move the egg from the surface of the ovary to the oviduct. Ciliated cells within the oviduct have motile hair-like structures on their surface that move gametes through the tube toward the uterus. Secretory cells within the oviduct secrete fluids that maintain the fluid environment of the tube that provides the normal in vivo site for fertilization of egg by sperm.

GIFT: Gamete intrafallopian tube transfer. This procedure combines eggs and sperm in the Fallopian tube, as occurs with natural fertilization. The major difference is that ovarian stimulation is used to generate a greater number of eggs and these eggs are returned to the Fallopian tube with semen that has been processed to enrich the number and quality of the sperm cells. The disadvantage is that more fertilized eggs may be produced in the Fallopian tubes than desired and thus increasing the risk of multiple gestation. Furthermore, if pregnancy fails to occur, it is impossible to determine if fertilization failed or if implantation failed.

Gonorrhea: A contagious inflammation of the genital mucous membrane with increased flow of mucous or exudates caused by the bacterium Neisseria gonorrhoeae. This infection is transmitted by sexual intercourse and may involve the lower or upper genital tract, especially the urthra, endocervix, and uterine tubes. In advanced untreated cases, the infection may spread to the peritoneum and rarely to the heart, joints and other structures via the blood stream.

Hepatitis B: A virus that is the ninth leading killer in the world. Hepatitis B virus is shed by blood, semen, vaginal secretions and saliva 4-6 weeks after symptoms develop. The virus may incubate, undetected for 6 months and some people are able to become asymptomatic carriers. The virus can be spread by contact with blood, semen and vaginal fluids and so can be spread by sexual intercourse. Presence of viral infection (acute) is determined by detection of viral surface and core antigens and previous exposure is determined by the presence of antibodies against the virus.

Hepatitis C: a virus that is responsible for infecting 150,000 people annually in the US and causing cirrhosis, liver failure and liver cancer. It is transmitted via contact with contaminated blood and sexual intercourse. Hepatitis C virus can remain in the blood for years, once the individual is infected. Detected by the presence of antibodies or viral DNA in the blood.

Human Immunodeficiency Virus (HIV) 1&2: Virus responsible for the autoimmune disease called AIDs which is characterized by wasting and increased susceptilbility to opportunistic infections. HIV is transmitted through blood or sexual intercourse.

Human T-cell Lymphotropic Virus I and II (HTLV I&II): HTLV is a retrovirus. HTLV-II virus has not been associated with any known disease. HTLV-I has been associated with two syndromes. One is called tropical spastic peripereisis, a degenerative disease of the nervous system, which is found in the Carribean and Japan. The second syndrome caused by Human T-cell Lymphotropic Virus I is Adult T-cell leukemia/lymphoma or ATLL.

Intrauterine Insemination (IUI): An artificial insemination procedure in which a processed semen ejaculate is placed directly into the uterus, bypassing the cervix and vagina. Ejaculated semen is processed in the laboratory to remove seminal plasma and optimize the semen parameters of motility and concentration while reducing the volume of sample. The processed sample is placed in a sterile catheter that is inserted through the vagina and cervix, allowing sperm to be expelled directly into the uterus. IUI is useful in cases of male factor when semen processing is desired to optimize a sample but the female is fertile. Because the sperm bypass the cervix and vagina, “hostile mucous” is avoided.

In vitro: literally, “in glass”; in vitro fertilization refers to fertilization of egg and sperm in a culture dish in the laboratory.

In vivo: literally, “in life”, referring to the natural state of fertilization or reproduction occurring inside the body.

Intracytoplasmic sperm injection: The injection of a single sperm cell into the cytoplasm of an egg. This procedure is most beneficial in cases in which the male partner has extremely low numbers of sperm or has another abnormality such as lack of motility, lack of acrosomal head structures, severe sperm antibodies that prohibit sperm entry by natural means. Indications for using ICSI have been expanded beyond male factor to include unexplained infertility and low egg number.  ICSI is also used to create embryos for preimplantation genetic diagnosis when the genetic test will employ polymerase chain reaction (PCR), a test which is extremely sensitive to contamination by DNA from other sources, like extra sperm.

In Vitro Fertilization: The fertilization of eggs and sperm when it occurs outside the body. In vitro literally means “in glass” and was used to distinguish laboratory events from those occurring naturally in the body or “in vivo”. Early culture dishes were made of glass but sterile disposable plastic culture dishes are the standard today.

Male factor: Male factor is a generic term for factors contributing to infertility which are attributed to the male; eg. Abnormal semen parameters such as zero or low numbers of sperm, poor sperm movement, low numbers of structurally normal sperm.

Normal Semen analysis: As defined by the World Health Organization (WHO) a normal semen analysis has the parameters shown below.

Parameter Normal Range (WHO, 4th edition)
Volume of ejaculate 2.0 ml or more
pH of ejaculate 7.2 or more
Sperm Concentration 20 million per ml or more
Total sperm number in the ejaculate 40 million or more
Percent Motility Over 50% motile and more than 25% with forward progressive motility
Percent Normal Sperm (Morphology) 15% or more
Vitality 50 % or more alive
White blood cells in ejaculate Fewer than 1 million per ml

It is important to know that semen parameters can change in a man’s sample over a period of time depending on many factors including age, drug use, medications and abstinence. To optimize your semen sample, abstinence of 2-3 days is ideal between ejaculations. It takes a little over 70 days for a sperm cell to be formed so improvements in semen analysis can be expected to require a minimum of two months of treatment or healthier living to see an effect. Also, it is not necessary for fertility that every parameter be normal. In cases of subfertility, some parameters may be subnormal which may translate into a longer duration of “trying” to produce a pregnancy. Other molecular defects, for instance, lack of receptors for egg-sperm binding or anti-sperm antibodies are not detectable in a routine semen analysis. Some of these defects have only been identified in the research setting and clinical assays have yet to be developed to detect these defects. `

Oligospermic: A subnormal concentration of sperm cells in the penile ejaculate. By WHO standards, less than 28.7 million cells per milliliter (about a teaspoon) of fluid. The normal range of semen concentration is between 28.7 and 338.9 million cells per milliliter.

Ovarian follicle: One of the spheroidal cell aggregations in the ovary containing an ovum or egg. The follicle enlarges as it grows and this enlargement is monitored by ultrasound during the course of superovulation treatments.

Polyspermy: The entrance of more than one sperm cell into the egg, resulting in an abnormal number of chromosomes not compatible with life.

Polar body: Chromosome-containing structures that are normally ejected by the egg as a consequence of the process of meiosis. Meosis is a biological process that gametes undergo to shuffle the genetic inheritance from the previous generation and produce haploid gametes capable of fertilization. Haploid simply means containing 23 chromosomes so that when the egg and sperm combine in fertilization, the total chromosomal number (46) for humans is achieved. The first polar body containing excess chromosomes is ejected following completion of egg maturation, the second polar body is ejected as a byproduct of fertilization.

Polygyny: The presence of two female pronuclei in the egg caused by the failure of the egg to eject the second female polar body at fertilization.

Preimplantation genetic diagnosis: The genetic analysis of embryonic cells from an 8-cell embryo to identify the genetic disease status (carrier, affected and non-affected) of each embryo tested. Typically, non-affected or carrier embryos (depending on the disease) are selected for transfer to the uterus, preventing the initiation of a pregnancy with an embryo that will suffer from a genetic disease.

Pronuclei: The nuclear material found in the egg (female pronucleus) or enclosed in the head of the sperm (male pronucleus). Two pronuclei in the egg cytoplasm indicate that fertilization has occurred.

Semen: the penile ejaculate; a fluid consisting of sperm cells and a mixture of secretions from the testis, seminal vesicles, prostate and bulbourethral glands. An appropriate mix of these secretions is necessary to maintain sperm function and fertility.

Sperm Concentration: the number of sperm cells in a sample divided by the volume of that sample.

Sperm Morphology: The shape and appearance of sperm cell structures. Normal sperm have a characteristic shape, defined by a ratio of the width and length of the head, the length and shape of the tail, the absence or duplication of head or tail structures. Curving or coiling of tail is considered abnormal.

Sperm Motility: The movement of sperm cells expressed as a percentage of all sperm in a sample (the percent motility). For example, in normal semen samples, greater than 40% of sperm cells will exhibit motion. The quality of that motion is also evaluated. Forward progressive motility (sperm moving forward in a straight line) is considered normal and desirable for achieving fertilization. Quivering or circular motion or extremely slow forward motion is considered abnormal sperm motility.

Syngamy: combination of the pronuclei (conjugation of gametes) from the male and female during fertilization.

Syphilis: An acute and chronic infectious disease caused by Treponema pallidum and transmitted by direct contact, usually by sexual intercourse.

ZIFT: Zygote intrafallopian tube transfer. This procedure differs from GIFT in that eggs are fertilized in vitro and the desired number of fertilized eggs can be transferred to the Fallopian tubes. The advantage is that fertilization success is confirmed and the number of fertilized eggs returned to the mother can be limited to reduce the risk of multiple gestation.

Zona pellucida: The mammalian “egg shell” composed of specific glycoproteins which function in sperm egg interaction at fertilization. One function of the zona pellucida is to limit the number of sperm that may enter the egg as well as the species specificity of sperm that enter the egg. During embryo development, the zona controls the spatial environment of the dividing embryonic cells and is lost just prior to implantation.

Zygote: The fertilized egg; identified by the presence of two pronuclei containing genetic material from the male and the female.