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Glossary

Abbreviations and Acronyms
AAB American Association of Bioanalysts, the organization that board certifies lab directors in the USA
AH Assisted Hatching
AI Artificial Insemination (see also AID, AIH, DI, TDI)
AID Artificial Insemination by Donor (no longer used, see DI, TDI)
AIH Artificial Insemination by Husband
ART Assisted Reproduction Technology
ASAB Anti-Sperm Antibody
BBT Basal Body Temperature
CASA Computer-Aided Sperm Analysis
CRYO Relating to cryopreservation
-D May be added to denote that donor spermatozoa were used, eg. IVF-D
DI Donor Insemination (formerly AID, see also TDI)
DMSO Dimethylsulphoxide (a cryoprotectant used for freezing embryos)
ET Embryo Transfer
FET Frozen Embryo Transfer
FF Follicular Fluid (see also hFF)
GEYC Glycerol-Egg Yolk Citrate (a modified Ackerman's cryoprotectant medium used to freeze semen)
GIFT Gamete Intra-Fallopian Transfer (by laparoscopy, ultrasound or mini-laparotomy)
HEPES Hydroxyethylpiperazine ethanesulphonic acid, a zwitterionic buffer used in culture media so that elevated carbon dioxide levels are not required to maintain their pH
HEPT Hamster Egg Penetration Test
hFF human Follicular Fluid (see also FF)
HSA Human Serum Albumin
HTF Human Tubal Fluid (a culture medium used for IVF developed by Patrick Quinn)
HZA Hemi-Zona Assay (a variant sperm-zona binding test, see also ZBT)
IBT Immunobead Test
ICSI Intracytoplasmic Sperm Injection
IUI Intra-Uterine Insemination
IVF In-Vitro Fertilization
IVF-ET In-Vitro Fertilization and Embryo Transfer
MSDS Material Safety Data Sheet
OPU Oocyte Pick-Up or retrieval
PCT Post-Coital Test
PN Pronucleus
PrOH Propanediol (a cryoprotectant used for freezing embryos)
PVP Polyvinylpyrrolidone
SCMC Sperm-Cervical Mucus Contact test
SFA Sperm Functional Assessment = Genesis-standard semen analysis
SMIT Sperm-Mucus Interaction Test (usually in-vitro, c/f. PCT)
SPA Sperm Penetration Assay (synonymous with HEPT)
TDI Therapeutic Donor Insemination (see DI)
TEST-Yolk See TYG
TYG TEST-yolk-glycerol, a common cryoprotectant for semen
TW Trial Wash, a pre-treatment sperm assessment including sperm preparation = Genesis “SpermScreen”
TZI Teratozoospermia Index, an assessment used in sperm morphology
US Ultrasound; sometimes USS = ultrasound scan(ning)
WBC White Blood Cell or leucocyte
WHMIS Workplace Hazardous Materials Information System
WHO World Health Organization
ZBT Sperm-Zona Binding Test (see also HZA)
ZIFT Zygote Intra-Fallopian Transfer (by laparoscopy or ultrasound)

 

Glossary

Because many specialist scientific and medical terms, as well as jargon, are used in everyday conversations in the ART laboratory, a glossary of the most common terms, abbreviations and acronyms is provided in this Appendix. If someone uses a term that you do not know or understand, ask that person or someone else in the laboratory – clear, concise and unambiguous communication is vital!

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Acrosin A trypsin-like protease enzyme that is contained inside the sperm acrosome (actually in its zymogen form, proacrosin) and is released by the acrosome reaction. It is believed that acrosin softens the glycoprotein structure of the zona pellucida and thereby facilitates sperm penetration through to the oocyte, and hence fertilization.
Acrosome An organelle of the spermatozoon that covers the anterior ½ to ⅔ of the sperm head. It contains acrosin in its zymogen form, proacrosin. See also acrosome reaction.
Acrosome reaction A process whereby the sperm plasma membrane forms localized fusions with the underlying outer acrosome membrane to create fenestrations through which acrosin is released. The acrosome reaction (AR) is induced in capacitated spermatozoa after binding to the sperm receptor, ZP3, on the zona pellucida. It is an essential part of the fertilization process, both in vivo and in vitro. See also capacitation.
Allele The term for a version or copy of DNA. For genes carried on the chromosomes inside the cell nucleus there are two copies or “alleles” present, although more versions may exist within the population.
Amniocentesis The sampling of fluid from the amniotic or gestational sac, usually performed around 14 weeks of pregnancy to check the genetic normality of the fetus by determining its karyotype or for performing biochemical tests.
Amplification see polymerase chain reaction
Aneuploidy A genetic abnormality caused by the absence or presence of one or more chromosomes, e.g. an extra chromosome 21 causes Down syndrome.
AR acrosome reaction
ART Assisted Reproductive Technology, the technical procedures underlying medically assisted conception.
Assisted hatching A micromanipulation process used to breach the zona pellucida and hence facilitate hatching of the blastocyst. Common approaches include the used of mechanical partial zona dissection (“PZD”), acid Tyrodes or a laser.
Asthenozoospermia A medical term often used to described low or poor sperm motility. However, since it does not describe any particular presentation, it is not considered a useful scientific term, and should be avoided. See also oligozoospermia, teratozoospermia and oligoasthenoteratozoospermia.
Atresia A process that occurs around the time of birth in mammals whereby the numbers of primordial follicles in the ovaries are greatly reduced.
Azoospermia The complete absence of spermatozoa in a man’s semen caused either by an obstruction or by failure to produce spermatozoa in the testes.
Blastocoel The fluid-filled cavity inside the blastocyst.
Blastocyst The stage of development at which the embryo is able to undergo implantation. Human embryos should reach this stage on Day 5 after fertilization. A blastocyst comprises an outer layer of cells, the trophoblast, that enclose the inner cell mass and a cavity, the blastocoel.
Blastomere A cell of a cleavage stage embryo, e.g. an 8-cell embryo has 8 blastomeres.
Centromere The central part of a chromosome. While this region does not contain any genes, it is highly specific for each chromosome allowing their identification using techniques such as FISH.
Capacitation The final stage of sperm maturation that normally occurs within the female tract after separation of the spermatozoon from the inhibitory decapacitation factors present in the seminal plasma. It is also required for fertilization in vitro, and the process must be supported by the culture medium. Capacitating spermatozoa display hyperactivated motility and, once capacitated, spermatozoa have the capacity to fertilize the oocyte, i.e. they are able to bind to the sperm receptor on the zona pellucida, (ZP3) and then undergo the acrosome reaction.
CASA Computer-aided sperm analysis, a technique that combines videomicrography with digital image analysis to analyze sperm movement patterns and derive kinematic measures that describe them. CASA technology is used to analyze sperm hyperactivation.
CFAS The Canadian Fertility and Andrology Society, the professional society in Canada comprising physicians, scientists, nurses and allied health professionals working in the field of reproductive biomedicine.
Chorionic villus sampling A CVS test is performed at about 10 weeks of pregnancy. Under ultrasound guidance a small sample of tissue is taken from the placenta for genetic testing, such as a karyotype.
Chromatin The complex formed by the DNA inside a cell’s nucleus when it is combined with regulatory and structural proteins.
Chromosome The visible structure formed by a single long strand of DNA with its supporting and regulatory proteins. There are 46 chromosomes in the nucleus of every human cell, 22 pairs of “autosomes” (common to both sexes) and the two sex chromosomes, XX in a female and XY in a male
Cleavage The process of repeated cell division whereby the fertilized oocyte or zygote divides into 2 daughter cells (the 2-cell embryo), each of which then divides into two, giving a 4-cell embryo, and so on.
Clone An organism that is identical to another, in terms of both its phenotype and its genotype.
Cloning The process whereby a clone is created.
COH controlled ovarian hyperstimulation
Controlled ovarian hyperstimulation see stimulation
Corona radiata  The innermost granulosa cells around the oocyte inside the follicle. During oocyte maturation the corona radiata cells extend processes through the zona pellucida and contact the oolemma. Although these processes are withdrawn at the end of oocyte maturation, the corona cells remain with the oocyte after ovulation. See also cumulus and oocyte-cumulus complex.
Corpus luteum The structure in the ovary created by the luteinized follicle. It secretes progesterone and supports the luteal phase of the female cycle. See also luteinization.
Culture medium (pl. = -dia) A solution of various salts and nutrients designed to sustain gametes and embryos during their incubation in vitro. See also sequential media.
Cumulus The cumulus cells are specialized granulosa cells that surround the oocyte after ovulation as a structure called the cumulus oophorus. See also corona radiata and oocyte-cumulus complex.
CVS see chorionic villus sampling
Cytogenetics The study of genetics at the level of the chromosomes, usually by preparing a karyotype.
Cytoplasm The liquid contained inside each cell in which structural components (e.g. the nucleus and the mitochondria) are suspended and the enzymes and other substances are dissolved.
Cytotoxic The effect of a substance (e.g. antibody or chemical) that causes the death of a cell.
Decapacitation factor Substance(s) in seminal plasma that inhibit sperm capacitation.
Deletion An abnormality of a DNA molecule where one (or more) nucleotide is missing. If this occurs inside a gene it can cause a genetic defect which can affect the individual’s phenotype.
Diploid The usual number of chromosomes in an organism, 46 in humans.
Diplospermy Fertilization that involves a diploid spermatozoon, and results in the formation of a triploid zygote without the appearance of three pronuclei.
Dispermy Fertilization of an oocyte by two spermatozoa that results in the formation of a triploid zygote with three pronuclei.
DNA Deoxyribonucelic acid, a molecule made up of a sequence of nucleotides, the order of which forms the genetic code of each individual animal or plant.
Dominant disorder A genetic defect that is expressed in the individual’s phenotype even if one only allele of the gene is abnormal.
Down syndrome  A genetic disability (sometimes called “mongolism”) caused by the presence of a third copy of chromosome 21.
E2 estradiol
Embryo A word used loosely to describe those stages of the development of an animal from the fertilized oocyte (i.e. zygote) until the fetus, i.e. about the first 8 weeks of human development; the stages before implantation are sometimes referred to as the pre-embryo.
Embryo biopsy The procedure whereby one or two cells are removed from an embryo (usually performed at the 8-cell stage on Day 3 after fertilization) for genetic analysis.
Endometrium The lining of the uterus that undergoes cyclical changes and, a few days after ovulation, is receptive to the blastocyst.
Epididymis (pl. = -mides) A coiled tubular organ attached to the side of the testis where sperm maturation and storage takes place. It is anatomically and functionally divided into three regions, the “head” (caput epididymidis), “body” (corpus epididymidis: sperm maturation) and “tail” (cauda epididymidis: sperm storage).
Enzyme A protein molecule that acts as a catalyst for a specific biochemical reaction.
Estradiol The primary circulating estrogen, it is measured during stimulation to monitor follicular development.
Fecundity The chance of becoming pregnant per cycle of trying.
Fertility The state of being fertile, i.e. of having a child.
Fertilization The fusion of the male and female gametes, a spermatozoon with an oocyte, to create a new individual. A fertilized oocyte is termed the zygote.
Fetal Of or pertaining to the fetus.
Fetus The state of development between the embryo and birth, i.e. from 8 weeks after fertilization until delivery for humans.
FISH fluorescent in-situ hybridization
Fluorescent in-situ hybridization A technique using fluorescently tagged pieces of synthetic DNA (“probes”) to label particular regions of a chromosome so that is can be seen under a fluorescence microscope using u.v. light.
Follicle The structure inside the ovary where the oocyte develops. During each cycle several follicles begin growing although typically all but one will regress (enter atresia) so that a single oocyte is released per cycle. With exogenous gonadotrophin treatment these other follicles do not regress and multiple oocytes can be aspirated for use in IVF. See also cumulus and granulosa.
Follicle stimulating hormone The gonadotrophin secreted by the pituitary during the follicular phase of the female cycle. FSH stimulates the follicles to grow and the granulosa cells to produce estradiol.
Follicular phase The first half of the female cycle during which folliculogenesis occurs and estradiol is secreted by the granulosa cells.
Folliculogenesis The process of follicle growth, a part of oogenesis
Fragile X syndrome A serious genetic disease caused by an abnormality of the X chromosome, specifically a variable expansion of a particularly fragile region. Females can carry this disease, but males are affected by it, causing developmental delays and mental retardation.
Free radicals see reactive oxygen species
FSH follicle stimulating hormone
Gamete The generic term for a male or female germ cell, i.e. the spermatozoon or oocyte.
Gametogenesis The process whereby gametes are produced; see oogenesis and spermatogenesis.
Gene A specific part of the DNA that contains the genetic code for a single molecule such as an enzyme or other protein.
Genome The entire genetic code of an individual cell or organism.
Genomics The study of the genome and gene expression.
Genotype The genetic description of an individual, as opposed to its physical description or phenotype.
Germinal vesicle A large, clear, circular nucleus visible inside the primary oocyte. Disappearance, or “breakdown” of the germinal vesicle (actually a prolonged late prophase stage of the first meiotic division) signals the primary oocyte’s resumption of meiosis.
Gonad The male or female reproductive organ responsible for producing gametes, i.e. the testis and ovary.
Gonadotrophin Any hormone that switches on and supports the function of the male or female gonads (i.e. the testes and ovaries).
Granulosa The granulosa cells surround the oocyte within the follicle. During the follicular phase of the female cycle they secrete estradiol but, in the luteal phase, they secrete progesterone (see also LH surge and luteinization). Specialized granulosa cells that form the oocyte-cumulus complex.
GV germinal vesicle
GVBD germinal vesicle breakdown
Haploid The genetic state of having only half the usual number of chromosomes (i.e. 23 in humans). This state is achieved in the gametes by the process of meiosis.
Hatching The term used to describe the process whereby the blastocyst is believed to escape from the zona pellucida prior to implantation. See also assisted hatching.
hCG Human chorionic gonadotrophin (more correctly β-hCG), a hormone that is produced by the early embryo and the ovary to regulate the early stages of pregnancy. Testing for increased levels of β-hCG is the basis of a pregnancy test. As a pharmaceutical, hCG is also given to “trigger” ovulation in women undergoing ovarian stimulation for IVF.
Homeostasis The physiological process(es) whereby the concentration of something, or a physico-chemical state, is maintained inside a cell or organism within a required range.
Hyaluronic acid A large polysaccharide (actually a glycosaminoglycan) that is the major constituent of the intercellular matrix, especially within the cumulus.
Hyaluronidase The enzyme whose substrate is hyaluronic acid.
Hybridization In this sense, the matching of two complementary strands of DNA.
Hyperactivated motility A highly energetic pattern of sperm movement which, when seen under the microscope, often appears non-progressive. It is caused by the development of high curvature waves in the sperm tail that are propagated at high velocity along the tail (“whiplash” motility), usually with a short delay. This causes the sperm head to display wide lateral displacement, and hence move in a characteristic “thrashing” pattern. Its expression (hyperactivation) is associated with sperm capacitation and is generally believed to be essential for sperm penetration through the zona pellucida, and hence both in vivo and in vitro fertilization.
Hyperactivation A change in the motility pattern of the spermatozoon associated with capacitation. See also hyperactivated motility.
ICSI see intracytoplasmic sperm injection
Implantation The process whereby the blastocyst stage embryo burrows into the lining of the uterus, or endometrium, to establish a pregnancy.
Infertility The state of being infertile, i.e. not being able to conceive a child.
Inner cell mass That part of the blastocyst that will give rise to the embryo proper, as opposed to the extra-embryonic membranes. See also trophoblast.
Interphase The stage in the cell cycle where the chromosomes are not visible in their characteristic form within the nucleus. See also metaphase.
Intracytoplasmic sperm injection A micromanipulation procedure whereby a single spermatozoon is inserted directly into the cytoplasm of the oocyte to achieve fertilization during IVF.
In-vitro culture The incubation of fertilized oocytes (zygotes) in the laboratory through the process of cleavage, typically up to the blastocyst stage of development.
In-vitro fertilization Literally, fertilization “in glass”. This technique, whereby oocytes and spermatozoa are mixed in the laboratory to achieve fertilization, is used as a treatment for infertility when the process cannot occur naturally inside the woman’s body.
In-vitro maturation The maturation of immature oocytes in the laboratory attempting to duplicate the natural process that occurs within the follicle.
In-vitro production The combined processes of in-vitro maturation, in-vitro fertilization and in-vitro culture whereby embryos are produced in the laboratory (i.e. IVP = IVM+IVF+IVC).
ISO The International Standards Organization comprising representation from the national standards institutes of more than 90 countries worldwide. Among many other standards, this organization produces the family of quality standards known as “ISO 9000” or, more correctly to reflect the publication of revised standards in 2000, “ISO 9000:2000”. For service-orientated businesses (e.g. ART units) the relevant standards are “ISO 9001:2000” (manufacturers are covered by “ISO 9002:2000”), whereas for specific application in laboratories, they are the “ISO/IEC 17025” standards.
IVC in-vitro culture
IVF in-vitro fertilization
IVM in-vitro maturation
IVP in-vitro production
Karyotype A preparation made from one or more cells in the laboratory to study whether an individual has a normal set of chromosomes. A normal male is 46,XY while a normal female is 46,XX. See also Down syndrome and translocation.
Kinematics Measurements that describe sperm movement patterns (e.g. hyperactivated motility), usually derived using CASA technology.
LH luteinizing hormone
LH surge A surge in LH secretion during the late follicular phase of the female cycle, caused by positive feedback of rising estradiol levels on the pituitary, that acts as the trigger for the final stages of oocyte maturation and ovulation.
Luteal phase The second half of the female cycle, during which the luteinized follicle or corpus luteum secretes progesterone and implantation of the blastocyst into the endometrium lining the uterus occurs. See also luteinization.
Luteinization The change in the granulosa cells of the follicle, induced by the LH surge, that causes their steroid hormone production to switch from estradiol to progesterone.
Luteinizing hormone The gonadotrophin that induces luteinization of the granulosa cells. See also LH surge.
Medium or Media Common terms for culture medium.
Meiosis A special type of cell division that occurs only during gametogenesis (i.e. oogenesis and spermatozogenesis) and results in the daughter cells, the gametes, having only half the usual number of chromosomes, i.e. being haploid.
MESA micro-epididymal sperm aspiration
Messenger RNA A molecule of RNA (“mRNA”) produced by transcription of a gene that carries the code for the product of that gene. This product is then produced by translation in the cytoplasm of the cell.
Metaphase The stage in the cell cycle immediately before it divides where all the chromosomes are visible and arranged in a single plane ready for division so that one copy of each goes to each daughter cell. See also interphase.
Micro-epididymal sperm aspiration A medical procedure whereby spermatozoa are aspirated from the epididymis, usually involving microsurgery.
Mitochondrion (pl.= -dria) structures inside every cell that resemble bacteria. These are the site of metabolism where carbohydrate is oxidized to release energy that is trapped as ATP for movement around the cell.
Mitosis The usual process of cell division whereby a cell divides into two identical “daughter” cells, e.g. during cleavage of the embryo.
Mitotic index The rate of cell division (mitosis) of a population of cells.
Molecular genetics The study of genetics at the level of individual genes or the DNA itself.
mRNA messenger RNA
mtDNA The small amount of DNA that carries the genetic code of the mitochondrion. It is the only DNA outside the cell nucleus and codes for 13 genes, which are essential in metabolism, and are not coded for by the nuclear DNA of the chromosomes.
Muscular dystrophy A group of neuromuscular diseases caused by specific genetic defects.
Mutation A change in the sequence of nucleotides in a DNA strand; see also deletion, point mutation.
Nuclear transfer The process by which the nucleus of one cell is removed and transferred into another cell; a basic technique used in cloning.
Nucleotide One of the four base chemicals that make up the double helix of DNA (adenine, cytosine, guanine, thymine). The order in which the four nucleotides occur in a stretch of DNA is called its sequence and constitutes the genetic code.
Nucleus The central part of each cell where the genetic code carried in the chromosomes reside.
OAT Syndrome see oligoasthenoteratozoospermia
OCC oocyte-cumulus complex
Oestradiol see estradiol
OHSS ovarian hyperstimulation syndrome
Oligoasthenozoospermia A medical term often used to described low or poor sperm motility combined with a low sperm concentration. However, since it does not describe any particular presentation, it is not considered a useful scientific term, and should be avoided. See also asthenozoospermia, oligozoospermia, and teratozoospermia.
Oligonucleotide A small piece of synthetic DNA often used as a primer in the polymerase chain reaction. It comprises a highly specific sequence of nucleotides designed to recognise a particular region of a gene.
Oligospermia An incorrect term, often used to describe a low sperm concentration; see oligozoospermia.
Oligozoospermia The medical term for having a very low sperm count (defined by the WHO as <20×106 spermatozoa per ml of semen).
Oocyte The correct scientific term for the female gamete, often referred to as the “egg”.
Oocyte-cumulus complex This structure, which is visible to the naked eye, comprises the oocyte, inside the zona pellucida, surrounded by the corona radiata cells and the cumulus oophorus; it is the structure found in follicular aspirates at oocyte retrieval.
Oocyte maturation A process that occurs during folliculogenesis whereby the oocyte becomes to competent to undergo fertilization and support early embryonic development. It comprises both nuclear and cytoplasmic processes, the former is visible as germinal vesicle breakdown and entry into meiosis (which is arrested at the metaphase II stage so that it is a secondary oocyte that is released at ovulation), while the latter involves the production and storage of a variety of essential mRNAs that will control development from fertilization through the time when the embryonic genome is activated (on Day 3, at about the 8-cell stage, in human embryos). See also in-vitro maturation.
Oocyte pickup  see oocyte retrieval
Oocyte retrieval The stage in the IVF process when the oocyte, more correctly the oocyte-cumulus complex (OCC) – usually several – are aspirated from the follicles of the ovary. Sometimes referred to as “oocyte pickup” or “OPU”.
Oogenesis The entire process whereby oocytes are produced in the ovary.
Oolemma The plasma membrane of the oocyte.
Ooplasm The cytoplasm of the oocyte.
OPU see oocyte pickup or oocyte retrieval
Ovarian hyperstimulation syndrome A complication of ovarian stimulation that can, in extreme cases, be fatal.
Ovary (pl. = ovaries) The female gonad where the female gametes (oocytes) are produced inside follicles by the process of oogenesis.
Ovulation The process whereby the (secondary) oocyte is released from the mature follicle on the surface of the ovary.
Ovum The female gamete after completion of meiosis. Since in humans (and many other mammals) the female gamete is released from the ovary as a secondary oocyte, and the second meiotic division is not completed until after incorporation of the spermatozoon at fertilization, the ovum stage never actually exists since at that time it is, strictly, already considered a fertilized oocyte, although not quite a zygote.
Partial zona dissection A micromanipulation process used to breach the zona pellucida using a fine glass needle. See also assisted hatching.
PCR see polymerase chain reaction
PGD see preimplantation genetic diagnosis
Phenotype The physical expression of the genetic makeup or genotype of an individual.
PN pronucleus
Point mutation An abnormality of a DNA molecule where a single nucleotide is changed. If this occurs inside a gene it can cause a genetic defect which can affect the individual’s phenotype.
Polar body A small cytoplasmic mass extruded by the oocyte during meiosis that contains a discarded set of chromosomes. The first polar body (1st PB) signals the completion of the first meiotic division and can be seen in the secondary oocyte; the second polar body (2nd PB) is extruded as a consequence of penetration of the oocyte by a spermatozoon and is an indication fertilization.
Polymerase chain reaction A molecular genetic technique that allows a single copy of a genetic sequence to be amplified geometrically to produce vast numbers of copies that can then be detected and analyzed. It uses a thermostable DNA polymerase enzyme and a repetitive sequence of temperature shifts in a “thermal cycler” machine to produce copies of a particular region of the genetic code located between a pair of carefully chosen primers.
Polymorphism The existence of multiple versions of a particular gene or sequence of genetic code.
Pre-embryo A non-scientific term commonly used in N. America to describe the embryo between the time of fertilization and implantation.
Preimplantation genetic diagnosis Testing performed on the cleavage stage embryo or blastocyst involving embryo biopsy and analysis of one or two cells using genetic techniques such as FISH or PCR.
Primary oocyte The stage of oogenesis when the female gamete undergoes the first meiotic division (see also meiosis).
Primer A small piece of synthetic DNA with a highly specific code for a particular region of a gene that can be used to initiate the polymerase chain reaction.
Primordial follicle A primitive stage of follicle within the ovary, especially numerous during the late fetal period. The number of primordial follicles is greatly reduced just around the time of birth by the process of atresia.
Probe A piece of synthetic DNA, usually with a fluorescent tag, used to identify particular regions of the chromosomes, e.g. in the technique of FISH.
Progesterone The hormone secreted by granulosa cells after luteinization, i.e. during the luteal phase of the female cycle. It is often given to help support the luteal phase in cycles where cryopreserved embryos are replaced due to deficient corpus luteum activity.
Pronucleus A structure formed during fertilization by the nuclear material contributed by each gamete, hence normal fertilization involves both a female pronucleus (created after extrusion of the second polar body) and a male pronucleus (formed, inside the ooplasm, from the decondensed chromatin of the sperm nucleus). A normal zygote has two pronuclei (“2PN”).
PZD partial zona dissection
QA quality assurance
QC quality control
QI quality improvement
Quality assurance Includes quality control, but is more expansive, encompassing quality control of the various component sub-processes and involving monitoring and control of the ultimate outcomes of the entire process.
Quality control Involves establishing specifications for each aspect of a process, assessing the procedures involved in the process to determine conformance to those specifications, and taking any necessary corrective actions to bring procedures into conformance.
Quality cycle A process within the framework of Total Quality Management whereby continuous cycles of quality assurance and quality improvement are undertaken.
Quality improvement The process whereby a procedure is reviewed and quality management principles used to bring about improvements in the actual procedure itself and/or its outcome(s).
Reactive oxygen species Damaging byproducts of oxidative metabolism that can cause severe damage to cells, including their membranes and DNA. Also sometimes called “free radicals”.
Recessive disorder A genetic defect that must be present in both alleles of a gene for it to be expressed in the individual’s phenotype.
Recombinant In this case, a substance produced artificially using molecular genetic engineering, e.g. the gonadotrophin hormones used in controlled ovarian hyperstimulation for IVF.
Ribonucleic acid A molecule used in the transcription of DNA, e.g. messenger RNA.
RNA ribonucleic acid
ROS reactive oxygen species
ROSI round spermatid injection
ROSNI round spermatid nucleus injection
Round spermatid A large, round, undifferentiated cell that is produced as a result of completion of the second meiotic division during spermatogenesis. The round spermatid enters spermiogenesis and differentiated into the spermatozoon.
Round spermatid injection An experimental procedure for achieving fertilization, similar to ICSI, whereby a round spermatid is injected into the oocyte. ROSI has very poor success rates.
Round spermatid nucleus injection An experimental procedure for achieving fertilization, similar to ICSI, whereby the isloated nucleus from a round spermatid is injected into the oocyte. ROSNI has very poor success rates.
SART The Society for Assisted Reproductive Technologies, a section of the American Society for Reproductive Medicine (ASRM), which runs a registry for ART results to which many Canadian clinics also report.
Secondary oocyte The stage of oogenesis when the female gamete undergoes the second meiotic division (see also meiosis). In humans (and many other mammals), the female gamete is released from the ovary (ovulation) at this stage, hence the female gamete is not actually an ovum.
Second polar body The 2nd PB is extruded as a consequence of penetration of the oocyte by a spermatozoon and is an indication fertilization.
Semen The male ejaculate, comprising spermatozoa and other cells suspended in a fluid the seminal plasma.
Semen analysis The procedure whereby the characteristics of the semen are measured, e.g. sperm concentration, motility, vitality, morphology. Sometimes referred to as a “seminal fluid analysis” or “SFA”, although this abbreviation is also used to mean “sperm functional assessment”.
Seminal plasma The liquid fraction of the semen, in which the spermatozoa are suspended. It is a mixture of secretions from the epididymis, prostate, seminal vesicles and other accessory glands of the male tract.
Seminiferous epithelium The epithelium lining the seminiferous tubules of the testis. This is where spermatogenesis takes place.
Seminiferous tubules U-shaped tubules, lined by the seminiferous epithelium, coiled inside separate lobes of the testis. They are the site of spermatogenesis.
Sequence The order in which the four nucleotides (adenine, cytosine, guanine, thymine) occur in a stretch of DNA, this constitutes the genetic code of a gene.
Sequential media A series of culture media designed to support an embryo during the various stages of its development in vitro, from fertilization to the blastocyst stage.
SFA see semen analysis
Spermatogenesis The process of male gametogenesis that occurs in the seminiferous epithelium lining the seminiferous tubules of the testis, whereby spermatozoa are produced. It includes cell divisions by both mitosis and meiosis as well as the differentiation process known as spermiogenesis.
Spermatozoon (pl.= -zoa) the correct scientific term for the male gamete, often referred to by the lay term “sperm”.
Spermiation The process whereby spermatozoa are released from the seminiferous epithelium into the lumen of the seminiferous tubules of the testis.
Spermiogenesis The highly complex process of differentiation whereby the round spermatid becomes a spermatozoon.
Sperm maturation A final process of maturation that spermatozoa undergo during passage through the epididymis. Unless this process is completed, spermatozoa are unable to fertilize oocytes via a normal process of fertilization, even in vitro.
Sterility The condition of being completely incapable of conceiving a child.
Stimulation The process by which multiple follicles are stimulated to grow, using gonadotrophin hormones, in a woman’s ovaries in a single cycle so that multiple oocytes can be collected for IVF. More correctly, this process should be referred to as controlled ovarian hyperstimulation (COH).
TESE testicular sperm extraction
Testicular sperm extraction A procedure whereby spermatozoa are retrieved from homogenized tissue obtained by testis biopsy.
Teratozoospermia A medical term often used to described poor sperm morphology. However, since it does not describe any particular presentation, it is not considered a useful scientific term, and should be avoided. See also asthenozoospermia, oligozoospermia, and oligoasthenoteratozoospermia and Teratozoospermia Index.
Teratozoospermia Index A index of the degree of sperm abnormality. A high TZI value is highly predictive of sperm dysfunction and hence impaired fertilizing ability.
Total quality management A management philosophy that combines quality control, quality assurance and quality improvement into a continuous, holisitic process of achieving and improving upon best practice by iterations of the quality cycle.
TQM total quality management
Transcription The copying of a strand of DNA (or a part of one, e.g. a gene), by a transcriptase enzyme, to make messenger RNA.
Transgenic An organism whose genotype has been modified by the insertion of a gene from another to produce individuals with one or more desired characteristics or traits.
Translation The decoding of a strand of RNA to produce a protein or “gene product”.
Translocation A genetic defect caused by the transfer of a part of one chromosome with, or onto another. This abnormality may be balanced, if parts of two chromosomes are exchanged so that the individual has a complete set of genetic information, but if any part is missing or a third copy of any part is present then it is unbalanced and can cause a problem.
Triploid An abnormal genetic state caused by the combination of three haploid sets of chromosomes at fertilization, usually revealed by the presence of three pronuclei in the zygote (typically caused by dispermy), althpugh it can also be caused by diplospermy or retention of the second polar body.
Trisomy A genetic defect caused by the presence of third copy of a chromosome, e.g Down syndrome.
Trophoblast The outer layer of cells of the blastocyst that will, after implantation, give rise to the extra-embryonic membranes.
TZI Teratozoospermia Index
WHO The World Health Organization
Xenotransplantation The transplantation of tissues or organs between different species (e.g. pig and human).
X- and Y-bearing spermatozoa Spermatozoa carrying X chromosomes will produce female offspring at fertilization, while sperm carrying Y-chromosomes will produce male offspring (since all oocytes carry only the X chromosome).
Zona pelludica The glycoprotein structure that surrounds the oocyte.
ZP zona pellucida
ZP3 “Zona protein 3”, a glycoprotein that is believed to be the sperm receptor in the zona pellucida.
Zygote The scientific term for a fertilized oocyte which then undergoes cleavage to form the 2-cell embryo or conceptus.

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