In-vitro Fertilization
-
Upload
renz-l-salumbre -
Category
Documents
-
view
932 -
download
4
description
Transcript of In-vitro Fertilization
In Vitro FertilizationHistory, Concepts and Issues
Renz L. SalumbreMS Zoology Program
Graduate SchoolUPLB
Generalities
Definition
“In Vitro” meaning “in glass”
Fusion of gametes outside the womb
Fertilization in a laboratory setting
Laboratory simulation
Test tube babies
Definition
Retrieval of more than one secondary oocyte from women who have received injections of follicle stimulating hormone and fertilizing these oocytes in vitro (Jansen, 2005)
DefinitionA method of assisted reproduction that involves combining an egg with sperm in a laboratory dish. If the egg fertilizes and begins cell division, the resulting embryo is transferred into the woman’s uterus where it will hopefully implant in the uterine lining and further develop. IVF may be performed in conjunction with medications that stimulate the ovaries to produce multiple eggs in order to increase the chances of successful fertilization and implantation. IVF bypasses the fallopian tubes and is often the treatment choice for women who have badlydamaged or absent tubes
Purpose
Enhancing productivity of food animals
Conservation of endangered animals
Specimens for embryological research
Treatment for infertility
Early History
Internal physiology was not yet fully understood
Rabbits and Hamsters were commonly used as laboratory specimens
Most researchers failed to provide sound evidence
Most researchers misinterpreted their results
The Golden Age
Discovery of sperm capacitation
In experiments, most sperms were capacitated in vivo before insemination
First use of a spermatozoa capacitated in vitro was reported in 1977
The Golden Age
In 1969, human eggs were fertilized in vitro
Sperm penetration
Polar body emission
Pronuclei emission
First IVF BabyCollaboration between Robert Edwards, a physiologist, and Patrick Steptoe, a gynecologist
First attempt produced an ectopic pregnancy
Initially employed a “natural” IVF
In July, 1978 the First IVF Baby, Louise Brown was born
Modern Age
Fertility Clinics
Assisted Reproduction Technology
Research
Stem Cell
Human Admixed Embryos
Methods
Methods
Ovarian Stimulation
Egg Retrieval
Insemination
Embryo Culture
Selection
Embryo Transfer
Ovarian Stimulation
Process is for 10 days but usually 8-14 days
Injection of hormones
gonadotropins e.g. FSH and FSH analogues
GnRH agonists/antagonists
Clomid
hMG
Stimulate egg production per menstrual cycle
Patients are closely monitored
Egg Retrieval
HCG is given as an LH analogue
The removal of eggs from the ovaries
Follicular aspiration or Transvaginal ultrasound aspiration
prior to HCG medication
Laparoscopic surgery may be employed
Insemination
Sperm is separated from the semen
Removal of seminal fluids and inactive cells
Added to a culture of eggs
Incubated
Embryo Culture
Fertilization
Incubation period of 18 hours
Confirmation of formation of pronuclei
2-4 cell after 2 days of fertilization
6-10 cell after 3 days of fertilization
Blastocyst after 5 days of fertilization
Culture Media
For in vitro culture of
follicles
male germinal cells
embryos
In the form of lyophilizate
Culture MediaContains hormones and growth factors in equilibrium concentrations
Growth factors
hepatic growth factor
Transformation growth factor (a)
granulocyte-macrophage colony stimulating factor
epidermal growth factor / heparin-binding EGF
Culture MediaGrowth and Differentiating Factors (GDF-9)
Insulin-like Growth Factors (IGF-1/IGF-2)
Corticoids preferable hydrocortisone
In hydrosoluble salt
in the form of hydrocortisone hemisuccinate
Coenzymes (NAD/NADH or NADP/NADPH)
Culture MediaIVF Kits include Upgraded B9 CCD culture medium
Mineral salts: KCl, NaCl, MgSO4, NaHCO3, Na2HPO4, KH2PO4
Essential Amino Acids including Glutamic Acid, Glycine, Taurine, Cystein, Glutamin
Metabolic Derivatives: Glucose, Pyruvate, Lactate, Acetate
Vitamins: B group and C
Purine and Pyrimidine Bases
Antibiotics: penicillin G, streptomycin
Selection
Oocyte and Embryo Quality
number of cells
evenness of growth
degree of fragmentation
6-10 cell stage are preferable
Blastocyst stage may also be transferred
Embryo Transfer
3 days after fertilization
Eggs are soaked in liquid
Cervical cleansing
Abdominal ultrasound
Eggs are transferred back to the uterus
Positive pregnancy if eggs attached to the uterine wall
Embryo Transfer3-day transfer
less costly and time-consuming
usually employed
risk of having many embryos implanted
Blastocyst transfer
much more effective and few embryos require
mimics natural process
costly
8-Cell Embryo for Transfer
Blastocyst for Embryo Transfer
Variant Methods
Intracytoplasmic Sperm Injection
ICSI is a recent micromanipulation technique
Single sperm is injected into the oocyte’s cytoplasm using a pipette
Addresses male infertility
azoospermia
oligospermia
asthenospermia
teratospermia
Hypospadias and reproductive problems in children conceived thru ICSI
Oocyte injected during ICSI
Zygote Intrafallopian Transfer
A highly invasive and very expensive ART procedure
Fertilized eggs are implanted into fallopian tubes by laparoscopy. Afterwards, it can pass down into the uterus to undergo normal pregnancy
Risk of having multifoetal pregnancy
ZIFT
Gamete Intrafallopian Transfer
Eggs are taken from the woman and combined with wash sperm
Immediately placed in the fallopian tube (ampullary region)
Process develops in a natural physiological manner
Bypasses egg pick-up of fallopian tube
Allegedly, the only artificial conception method accepted by the Roman Catholic Church
Tubal Embryo Transfer
Embryos are transferred to the fallopian tube
Used in conjunction with ZIFT
For patients who have difficult transcervical intrauterine transfer
Issues
SurrogacyTwo types
Traditional
surrogate is genetically related to the child
Gestational
• surrogate is not genetically related to the child
• Legal and psychological problems
Assisted Hatching
• Improves implantation and specifically for patients with poor IVF results
• Also lessens the number of embryo being transferred
• A micromanipulation technique that creates a small hole in the zona pellucida of the embryo
• Risk of damaging the embryo
Prevention of Genetic Diseases
• Preimplantation Genetic Diagnosis (PGD)
• Embryo screening
• Searches for unhealthy embryo
• Limits development of genetic diseases
Cryopreservation
• Unused eggs are stored for future use
• Excess embryos which are not implanted are preserved to be further used when prior IVFs are unsuccessful
Sex Selection
• Preconception gender selection through sperm separation
• Albumin gradients
• Percoll gradients
• Sephadex columns
• Swim-up techniques
• Flow cytometry
Ethical Considerations
• Objection to artificial conception
• Conception must be an act of the consummation of marriage
• Rights of the child to be born
• Unregulated experimentation on human embryos
• Does not give importance on human life
• “Playing” God
Financial Consideration
• In vitro Fertilization costs $12,000
• Gestational Surrogates cost $10,000
• Availability in third-world countries
Biological Risks• Ovarian Hyperstimulation Syndrome
• Infection and damaging of other structures during laparoscopy
• Multiple Pregnancy
• Underweight Infants by IVF
• Increased likelihood of having a handicap child
• Impediment of normal process may lead to complications of normal physiological processes
Biological Risk
• Large Offspring Syndrome
• Survivor’s Syndrome
• Angelman Syndrome
• Beckwith-Wiedeman Syndrome
• Retinoblastoma
• Chimerism
References• American Society for Reproductive Medicine. Patient’s Fact Sheet : Intracytoplasmic Sperm Injection.
http://www.asrm.org. Created August, 2001.
• American Society for Reproductive Medicine. (2006). Third party reproduction: A guide for patients. http://www.asrm.org.
• Bavister, B.D. Early history of in vitro fertilization. Reproduction 2002; 124, 181-196.
• Bellini, C (interview). In vitro children and the risks they face. http://www.zenit.org/article-10293?|=english. Created June 6, 2006.
• Choay, P. & S. Weinman. Cellular culture medium, particularly for in vitro fertilization, or for the culture of follicles, male germ cells or embryos. (August 26, 2003). United States Patent.
• Ethics Committee of the American Society for Reproductive Medicine. Preconception gender selection for nonmedical reasons. Fertility and Sterility 2001; 75; 5: 861-864.
• Jansen, R.P.S. Benefits and challenges brought by improved results from in vitro fertilization. Internal Medicine Journal 2005; 35: 108-117.
• http://www.sharedjourney.com
• Ratzinger, J. Instruction on respect for human life in its origin and on the dignity of procreation: Replies to certain questions of the day. Congregation for the Doctrine of the Faith. February, 1987. http://www.vatican.va
• Wikipedia.org. In vitro fertilisation. http://en.wikipedia.org/wiki/In_vitro_fertilization. Retrieved August 19, 2008.