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< |
