Delhi Public School, Noida
Biology CBSE Project
Submitted By: Chhavi Singh Xii- Science
Acknowledgements… I would like to pay my heartfelt thanks to my subject teacher __________________________________ for guiding me throughout this tenure. I would also like to thank my family and friends for helping me in this project.
Certificate This is to certify that the Project work has been satisfactorily completed under my guidance and supervision by Ms. Chhavi Singh, student of XIIth Science.
T. Signature
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Index Topic Definition & Meaning Brief Discussion Examples Detailed study of In-vitro fertilization Method Success Rates Expansion of IVF Risks Bibliography
Topic : Assisted Reproductive Technologies (Case Study)
Definition & Meaning
Assisted reproductive technology (ART) a general term referring to methods used to achieve pregnancy by artificial or partially artificial means. It is reproductive technology used primarily in infertility treatments. Some forms of ART are also used in fertile couples for genetic reasons. ART is also used in couples who are discordant for certain communicable diseases, e.g. AIDS, to reduce the risk of infection when a pregnancy is desired. Examples of ART include in vitro fertilisation, intra-cytoplasmic sperm injection (ICSI), cryopreservation, and intrauterine insemination (IUI). There is yet no strict definition of the term. Usage of the ART mainly belongs in the field of reproductive endocrinology and infertility.
Definition: The Centres for Disease Control and Prevention (CDC)—which is required as a result of the 1992 Fertility Clinic Success Rate and Certification Act to publish the annual ART success rates at U.S. fertility clinics—defines ART to include "all fertility treatments in which both eggs and sperm are handled. In general, ART procedures involve surgically removing eggs from a woman's ovaries, combining them with sperm in the laboratory, and returning them to the woman's body or donating them to another woman." According to CDC, "they do not include treatments in which only sperm are handled (i.e., intrauterine—or artificial—insemination) or procedures in which a woman takes medicine only to stimulate egg production without the intention of having eggs retrieved."
Brief Discussion ART has been used in the United States since 1981 to help women become pregnant, most commonly through the transfer of fertilized human eggs into a woman’s uterus (in vitro fertilization). However, deciding whether to undergo this expensive and time-consuming treatment can be difficult.
According to CDC’s 2010 ART Success Rates, 147,260* ART cycles were performed at 443 reporting clinics in the United States during 2010, resulting in 47,090 live births (deliveries of one or more living infants) and 61,564 infants. Although the use of ART is still relatively rare as compared to the potential demand, its use has doubled over the past decade. Today, over 1% of all infants born in the U.S. every year are conceived using ART. *Excludes cycles in which a new treatment procedure was being evaluated.
The National Institute of Child Health and Human Development held a workshop on September 12-13, 2005, to summarize the risks for adverse pregnancy outcomes after assisted reproductive technology (ART), develop an approach to counseling couples regarding these risks, and establish a research agenda. Although the majority of ART children are normal, there are concerns about the increased risk for adverse pregnancy outcomes. More than 30% of ART pregnancies are twins or higher-order multiple gestations (triplets or greater) and more than one half of all ART neonates are the products of multifetal gestations, with an attendant increase in prematurity complications. Assisted reproductive technology singleton pregnancies also demonstrate increased rates of perinatal complications-small for gestational age infants, preterm delivery, and perinatal mortality-as well as maternal complications, such as preeclampsia, gestational diabetes, placenta previa, placental abruption, and cesarean delivery. Although it is not possible to separate ART-related risks from those secondary to the underlying reproductive pathology, the overall increased frequency of obstetric complications, including preterm birth and small for gestational age neonates, should be discussed with the couple. Significant gaps in knowledge were identified, and the basic science and clinical and epidemiologic research required to address these gaps is outlined.
Examples Artificial Insemination Cloning Embryonic splitting or cleavage Cryopreservation of sperms, oocytes or embryos Embryo transfer Fertility medication Hormone treatment In-vitro fertilization Intra-cytoplasmic sperm injection Pre-implantation genetic diagnosis
Artificial Insemination
Artificial insemination (AI) is the deliberate introduction of semen into a female for the purpose of fertilisation, by means other than ejaculation directly into the vagina or oviduct. Artificial insemination is a fertility treatment for humans, and is a common practice in the breeding of dairy cattle and pigs. Artificial insemination may employ assisted reproductive technology, donated sperm, and/or animal husbandry techniques.
In Humans Artificial insemination is a means for a woman to conceive when she does not have a male partner, when she does not want a male partner, or when a male partner's sexual inhibition or physical limitation impedes his ability to impregnate her by sexual intercourse. Women who have issues with the cervix such as cervical scarring, cervical blockage from endometriosis, or thick cervical mucus also benefit from AI since the sperm must pass through the cervix to result in fertilization.
Cloning
Human cloning is the creation of a genetically identical copy of a human. It does not refer to monozygotic multiple births or the reproduction of humans/animals cells or tissue. The ethics of cloning is an extremely controversial issue. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.
There
are
two
commonly
discussed
types
of
human
cloning: therapeutic
cloning and reproductive cloning. Therapeutic cloning involves cloning cells from an adult for use in medicine and transplants, and is an active area of research. Reproductive cloning would involve making cloned humans, for couples wanting to have a child, but cannot naturally.
Embryonic splitting or cleavage
In embryology, cleavage is the division of cells in the early embryo. The zygotes of many species undergo rapid cell cycles with no significant growth, producing a cluster of cells the same size as the original zygote. The different cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula. Depending mostly on the amount of yolk in the egg, the cleavage can be holoblastic (total or entire cleavage) or meroblastic (partial cleavage). The pole of the egg with the highest concentration of yolk is referred to as the vegetal pole while the opposite is referred to as the animal pole. Cleavage differs from other forms of cell division in that it increases the number of cells without increasing the mass. This means that with each successive subdivision, the ratio of nuclear to cytoplasmic material increases.
Cryopreservation of sperms, oocytes or embryos
Cryopreservation is a process where sperms, oocytes and embryos are preserved by cooling to sub-zero temperatures, typically 77 K (= −196 °C, the boiling point of liquid nitrogen). At these cold temperatures, any biological activity, including the biochemical reactions that would cause cell death, is effectively stopped. However, if cryoprotectant solutions are not used, the cells being preserved are likely to be damaged due to freezing during the cooling or thawing process.
Embryo Transfer
Embryo transfer refers to a step in the process of assisted reproduction in which embryos are placed into the uterus of a female with the intent to establish a pregnancy. This technique (which is often used in connection with in vitro fertilization (IVF)), may be used in humans or in animals, in which situations the goals may vary.
Fertility Medication
Fertility medication are drugs which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary. There are currently very few fertility medication options available for men.
Hormone Treatment
Hormone treatment or hormonal therapy is the use of hormones in medical treatment. Treatment with hormone antagonists may also referred to as hormonal therapy.
In-vitro fertilization
In vitro fertilization (IVF) is the technique of letting fertilization of the male and female gametes (sperm and egg) occur outside the female body. Techniques usually used in in vitro fertilization include:
Transvaginal ovum retrieval (OCR) is the process whereby a small needle is inserted through the back of the vagina and guided via ultrasound into the ovarian follicles to collect the fluid that contains the eggs.
Embryo transfer is the step in the process whereby one or several embryos are placed into the uterus of the female with the intent to establish a pregnancy
Intra-cytoplasmic sperm injection
Intracytoplasmic sperm injection (ICSI) is a procedure in which a single sperm is injected directly into an egg. This procedure is most commonly used to overcome male infertility problems, although it may also be used where eggs cannot easily be penetrated by sperm, and occasionally in addition tosperm donation. It can be used in teratozoospermia, because once the egg is fertilized, abnormal sperm morphology morphology.
does [3]
not
appear
to
influence blastocyst development
or
blastocyst
Even with severe teratozoospermia, microscopy can still detect the few sperm
cells that have a "normal" morphology, allowing for optimal success rate.
pre-implantation genetic diagnosis
In medicine and (clinical) genetics pre-implantation genetic diagnosis (PGD or PIGD) (also known as embryo screening) refers to procedures that are performed on embryos prior toimplantation, sometimes even on oocytes prior to fertilization. PGD is considered another way to prenatal diagnosis. When used to screen for a specific genetic disease, its main advantage is that it avoids selective pregnancy termination as the method makes it highly likely that the baby will be free of the disease under consideration. PGD thus is an adjunct to assisted
reproductive
technology,
obtain oocytes or embryos for evaluation.
and
requires in
vitro
fertilization (IVF)
to
Detailed study of In-vitro fertilization In vitro fertilisation (IVF) is a process by which an egg is fertilised by sperm outside the body: in vitro. IVF is a major treatment for infertility when other methods of assisted reproductive technology have failed. The process involves monitoring a woman's ovulatory process,
removing ovum
or
ova(egg
or
eggs)
from
the
woman's ovaries and
letting sperm fertilize them in a fluid medium in a laboratory. When a woman's natural cycle is monitored to collect a naturally selected ovum (egg) for fertilisation, it is known as natural cycle IVF. The fertilised egg (zygote) is then transferred to the patient'suterus with the intention of establishing a successful pregnancy. The first successful birth of a "test tube baby", Louise Brown, occurred in 1978. Louise Brown was born as a result of natural cycle IVF. Robert G. Edwards, the physiologist who developed the treatment, was awarded the Nobel Prize in Physiology or Medicine in 2010.
The term in vitro, from the Latin meaning in glass, is used, because early biological experiments involving cultivation of tissues outside the living organism from which they came, were carried out in glass containers such as beakers, test tubes, or petri dishes. Today, the term in vitro is used to refer to any biological procedure that is performed outside the organism it would normally be occurring in, to distinguish it from an in vivo procedure, where the tissue remains inside the living organism within which it is normally found. A colloquial term for babies conceived as the result of IVF, "test tube babies", refers to the tube-shaped containers of glass or plastic resin, called test tubes, that are commonly used in chemistry labs and biology labs. However, in vitro fertilisation is usually performed in the shallower containers called Petri dishes. One IVF method, Autologous Endometrial Coculture, is actually performed on organic material, but is still considered in vitro.
IVF may be used to overcome female infertility in the woman due to problems of the fallopian tube, making fertilisation in vivo difficult. It may also assist in male infertility, where there is a defect in sperm quality, and in such cases intracytoplasmic sperm injection (ICSI) may be used, where a sperm cell is injected directly into the egg cell. This is used when sperm have difficulty penetrating the egg, and in these cases the partner's or a donor's sperm may be used. ICSI is also used when sperm numbers are very low. ICSI results in success rates equal to those of IVF. For IVF to be successful it typically requires healthy ova, sperm that can fertilise, and a uterus that can maintain a pregnancy. Due to the costs of the procedure, IVF is generally attempted only after less expensive options have failed. IVF can also be used with egg donation or surrogacy where the woman providing the egg isn't the same who will carry the pregnancy to term. This means that IVF can be used for females who have already gone through menopause. The donated oocyte can be fertilised in a crucible. If the fertilisation is successful, the embryo will be transferred into the uterus, within which it may implant. IVF can also be combined with preimplantation genetic diagnosis (PGD) to rule out presence of genetic
disorders.
A
similar
but
called Preimplantation Genetic Haplotyping
more
general
test
has
been
developed
Method Theoretically, in vitro fertilisation could be performed by collecting the contents from a woman's fallopian tubes or uterus after natural ovulation, mixing it with semen, and reinserting into the uterus. However, without additional techniques, the chances of pregnancy would be extremely small. Such additional techniques that are routinely used in IVF include ovarian hyper stimulation to retrieve multiple eggs, ultrasound-guided transvaginal oocyte retrieval directly from the ovaries, egg and sperm preparation, as well as culture and selection of resultant embryos before embryo transfer back into the uterus.
Egg & Sperm Preparation
In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilisation. An oocyte selection may be performed prior to fertilisation to select eggs with optimal chances of successful pregnancy. In the meantime, semen is prepared for fertilisation by removing inactive cells and seminal fluid in a process called sperm washing. If semen is being provided by a sperm donor, it will usually have been prepared for treatment before being frozen and quarantined, and it will be thawed ready for use.
Fertilization The sperm and the egg are incubated together at a ratio of about 75,000:1 in the culture media for about 18 hours. In most cases, the egg will be fertilised by that time and the fertilised egg will show two pronuclei. In certain situations, such as low sperm count or motility, a single sperm may be injected directly into the egg using intracytoplasmic sperm injection (ICSI). The fertilised egg is passed to a special growth medium and left for about 48 hours until the egg consists of six to eight cells. In gamete intrafallopian transfer, eggs are removed from the woman and placed in one of the fallopian tubes, along with the man's sperm. This allows fertilisation to take place inside the woman's body. Therefore, this variation is actually an in vivo fertilisation, not an in vitro fertilisation.
Embryo Culture
Typically, embryos are cultured until having reached the 6–8 cell stage three days after retrieval. In many Canadian, American and Australian programmes, however, embryos are placed into an extended culture system with a transfer done at the blastocyst stage at around five days after retrieval, especially if many good-quality embryos are still available on day 3. Blastocyst stage transfers have been shown to result in higher pregnancy rates.[9] In Europe, transfers after 2 days are common. Culture of embryos can either be performed in an artificial culture medium or in an autologous endometrial coculture (on top of a layer of cells from the woman's own uterine lining). With artificial culture medium, there can either be the same culture medium throughout the period, or a sequential system can be used, in which the embryo is sequentially placed in different media. For example, when culturing to the blastocyst stage, one medium may be used for culture to day 3, and a second medium is used for culture thereafter. Single or sequential medium are equally effective for the culture of human embryos to the blastocyst stage. Artificial embryo culture media basically contain glucose, pyruvate, and energy-providing components, but the addition of amino acids, nucleotides, vitamins,
and
cholesterol
improve
the
performance
of
embryonic
growth
and
development. Methods to permit dynamic embryo culture with fluid flow and embryo movement are also available. A new method in development uses the uterus as an incubator and the naturally occurring intrauterine fluids as culture medium by encapsulating the embryos in permeable intrauterine vessel.
Embryo Selection & transfer Laboratories have developed grading methods to judge oocyte and embryo quality. In order to optimise pregnancy rates, there is significant evidence that a morphological scoring system is the best strategy for the selection of embryos. However, presence of soluble HLA-G might be considered as a second parameter if a choice has to be made between embryos of morphologically equal quality. Also, two-pronuclear zygotes (2PN) transitioning through 1PN or 3PN states tend to develop into poorer-quality embryos than those that constantly remain 2PN.
Embryos are failed by the embryologist based on the amount of cells, evenness of growth and degree of fragmentation. The number to be transferred depends on the number available, the age of the woman and other health and diagnostic factors. In countries such as Canada, the UK, Australia and New Zealand, a maximum of two embryos are transferred except in unusual circumstances. In the UK and according to HFEA regulations, a woman over 40 may have up to three embryos transferred, whereas in the USA, younger women may have many embryos transferred based on individual fertility diagnosis. Most clinics and country regulatory bodies seek to minimise the risk of pregnancies carrying multiples, as it is not uncommon for more implantations to take than desired. The embryos judged to be the "best" are transferred to the patient's uterus through a thin, plastic catheter, which goes through her vagina and cervix. Several embryos may be passed into the uterus to improve chances of implantation and pregnancy.
Success Rates IVF success rates are the percentage of all IVF procedures which result in a favorable outcome. Depending on the type of calculation used, this outcome may represent the number of confirmed pregnancies, called the pregnancy rate or number of live births, called the live birth rate. Due to advancement in reproductive technology, the IVF success rates are substantially better today than they were just a few years ago. The most current data available in the United States a 2009 summary complied by the Society for Reproductive Medicine which reports the average national IVF success rates per age group using non-donor eggs.
Expansions of IVF In zygote intrafallopian transfer (ZIFT), egg cells are removed from the woman's ovaries and fertilized in the laboratory; the resulting zygote is then placed into the fallopian tube. The following are techniques generally requires methods of in vitro fertilisation. In vitro fertilization, however, usually does not require these techniques.
Assisted zona hatching (AZH) is performed shortly before the embryo is transferred to the uterus. A small opening is made in the outer layer surrounding the egg in order to help the embryo hatch out and aid in the implantation process of the growing embryo.
Intracytoplasmic sperm injection (ICSI) is beneficial in the case of male factor infertility where sperm counts are very low or failed fertilization occurred with previous IVF attempt(s). The ICSI procedure involves a single sperm carefully injected into the center of an egg using a microneedle. This method is also sometimes employed when donor sperm is used.
Autologous endometrial coculture is a possible treatment for patients who have failed previous IVF attempts or who have poor embryo quality. The patient's fertilized eggs are placed on top of a layer of cells from the patient's own uterine lining, creating a more natural environment for embryo development.
Cytoplasmic transfer is the technique in which the contents of a fertile egg from a donor are injected into the infertile egg of the patient along with the sperm.
Egg donors are resources for women with no eggs due to surgery, chemotherapy, or genetic causes; or with poor egg quality, previously unsuccessful IVF cycles or advanced maternal age. In the egg donor process, eggs are retrieved from a donor's ovaries, fertilized in the laboratory with the sperm from the recipient's partner, and the resulting healthy embryos are returned to the
recipient's uterus. Sperm donation may provide the source for the sperm used in IVF procedures where the male partner produces no sperm or has an inheritable disease, or where the woman being treated has no male partner.
A gestational carrier is an option when a patient's medical condition prevents a safe pregnancy, when a patient has ovaries but no uterus due to congenital absence or previous surgical removal, and where a patient has no ovaries and is also unable to carry a pregnancy to full term.
Preimplantation genetic diagnosis (PGD) involves the use of genetic screening mechanisms such as Fluorescent In Situ Hybridization (FISH) or Comparative Genomic Hybridization (CGH) to help identify genetically abnormal embryos and improve healthy outcomes.
Embryo splitting can be used for twinning to increase the number of available embryos.
Risks The risk of birth defects in infants born following assisted reproductive technology (ART) treatment is a controversial question. Most publications examining the prevalence of birth defects in ICSI and IVF infants compared to spontaneously conceived infants have serious methodological limitations; despite this, most researchers have concluded that there is no increased risk. METHODS: We carried out a systematic review to identify all papers published by March 2003 with data relating to the prevalence of birth defects in infants conceived following IVF and/or ICSI compared with spontaneously conceived infants. Independent expert reviewers used criteria defined a priori to determine whether studies were suitable for inclusion in a meta-analysis. Fixed effects meta-analysis was performed for all studies and reviewer-selected studies. RESULTS: Twenty-five studies were identified for review. Two-thirds of these showed a 25% or greater increased risk of birth defects in ART infants. The results of meta-analyses of the seven reviewer-selected studies and of all 25 studies suggest a statistically significant 30–40% increased risk of birth defects associated with ART.
CONCLUSIONS: Pooled results from all suitable published studies suggest that children born following ART are at increased risk of birth defects compared with spontaneous conceptions. This information should be made available to couples seeking ART treatment.
Bibliography www.google.com www.wikipedia.com Various magazines and newspapers
