in vitro fertilization

ASSISTED REPRODUCTIVE TECHNOLOGIES

By,DAMARIS BENNY DANIELII Msc. ZOOLOGY

INTRODUCTION

Medically assisted human reproductive technologies are a group of high tech treatment methods used to combat infertility.

One of the greatest advances in reproductive medicine

Techniques includeIntrauterine Insemination (IUI)In Vitro Fertilization and

Embryo transfer (IVF – ET)Gametic Intra-Fallopian Transfer (GIFT)Zygotic Intra-Fallopian Transfer (ZIFT)Tubal embryo stage transfer (TET)Intracytoplasmic sperm injection (ICSI)

CAUSES OF INFERTILITYIn males

Oligospermia – reduced conc. of sperm in semen.Azoospermia – Total lack or very low conc. of motile sperm

In femalesTubal infertility – non functional fallopian tubeNon functional ovariesNon functional uterusEndometriosis - Endometrial-like cells in areas

outside the uterus Idiopathic infertility – reason unknown.

INTRA UTERINE INSEMINATION (IUI)Women (with adequate

ovulation & below 40yrs) without damage to fallopian tube can be treated with IUI.

Women superovulated by gonadotrophins – multiple egg dev.

IUI is timed to coincide with ovulation

Using a thin soft catheter, sperms are placed either in the cervix or in the utrine cavity.

ADVANTAGESThis procedure can be an effective solution for men with a low

sperm count or poor sperm motility, where the sperm can't make the long journey to the egg.

Low cost compared to other ART .

DISADVANTAGESTiming in the process of insemination is important.Low success rate, results are only 10-20 % Fallopian tubes must be unobstructed

IN VITRO FERTILIZATION

IVF broadly deals with the removal of eggs from a women, fertilizing them in the laboratory and then transferring the fertilized eggs into uterus a few days later.

Infertility due to the following causes may be considered for IVFFailed ovulation inductionTubal diseasesEndometriosisIdiopathic infertility

GENERAL PROTOCOLPatient selectionManipulation of mensural

cycle; superovulationOocyte retrievalPreparation of semen

sampleIVF treatmentEmbryo transferCryopresevation

1) PATIENT SELECTIONCriteria

Woman below 35yrsPresence of atleast one functional ovaryHusband with normal motile sperm countThe couple must be negative for HIV and hepatitis.

2) INDUCTION OF SUPEROVULATION1 week before next menstural period – leuprolide injection –

prevent premature release of egg.Within 2 week of onset of menstural period – FSH injection –

stimulates maturation of multiple eggs.Then a single injection of HCG (Human Chorionic Gonadotropin)

is given – triggers final stage of egg maturation. Ovulation will occur between 24–36 hours after the HCG injection.

3) OOCYTE RETRIEVALEggs are retreived after 36 hrs of HCG injection.Most common - through vaginal route under ultrasound

guidance.Needle enters the ovarian follicle and aspirate the fluid from

themIt is examined under microscope to identify eggs.

4) PREPARATION OF SEMEN SAMPLESemen collected from the partner.Processed and incubated in protein supplemented media for

3-4 hrs – rslts in sperm capacitation.

5) IVF TREATMENTCapacited sperms placed in culture with a single oocyte in a

petridish.Signs of fertilization – presence of 2 pronuclei

6) EMBRYO TRNSFER4 – 8 cell stage embryos are transferredTransferred with the help of a catheter.Catheter is passed through the cervical canal and embryos are

released to the top part of the uterus.Not more than 3 embryos are transferred.

7) CRYOPRESERVATION

Preservation in frozen state is regarded as cryopreservation.

Semen, fertilized eggs and embryos can be cryopreserved.Human embryos have been successfully preserved in the

presence of cryoprotectant like 1, 2 propanediol or dimethyl sulphoxide or glycerol.

It was stored at -196OC under liquid nitrogen.At appropriate time, the embryos are thawed and is transferred

to uterus.

ADVANTAGESFertilization is confirmed before implantation can occur.Gives women with damaged oviducts, the opportunity to carry

their own fetus.

DISADVANTAGESImplantation in the uterus does not always occur.Higher risk of twins or triplets, which also increases the risk

of complications and miscarriages.Side effects associated with the fertility medicationHigher risk of ectopic pregnancy, especially in women that

have had previous problems with their oviducts

It involves the transfer of both sperm and unfertilized oocyte into the fallopian tube.

This allows the fertilization to naturally occur in vivo.Two oocyte along with 2 – 5 lakhs motile sperms are placed in a

plastic tube container.Then oocyte sperm combination is injected 4cm into the distal

end of fallopian tube.

GAMETE INTRA FALLOPIAN TRANSFER (GIFT)

ADVANTAGESThere is no much human intervention in the actual

fertilization of the eggs.Because fertilisation takes place within the fallopian tube,

GIFT offers an option for people whose religious beliefs prohibit conception outside the body.

DISADVANTAGESCan be performed only if woman have atleast one normal

fallopian tube.GIFT does not allow for visual confirmation of fertilisation.GIFT involves a laproscopic surgery.

ZIFT combines aspects of both IVF and GIFT.

Fertilization takes place outside the uterus and placed into the fallopian tubes

Protocols for ovarian stimulation are similar to those used for IVF and GIFT.

Eggs are collected and fertilized by the partner’s sperm in the laboratory.

The zygote is transferred to the fallopian tube within 24hrs, when it is at 1 cell stage.

ZYGOTE INTRA FALLOPIAN TRANSFER (ZIFT)

ADVANTAGESFertilization can be confirmed before they are implanted into

the fallopian tube.Allows a developing embryo to travel into the uterus on its

own, which may be important to those who wish their baby to develop as naturally as possible

DISADVANTAGESCan be performed only if woman have atleast one normal

fallopian tube.It is more expensive than GIFT.ZIFT involves a laproscopic surgery.

TUBAL EMBRYO STAGE TRANSFER (TET)It combines IVF with tubal transferEmbryos are placed into the women’s fallopian tube.The embryos are transferred back into the woman 2 days after

fertilisation. This is at the ‘2 cell or 4 cell’ stage.TET allows embryos to make their way to the uterus for

implantation.Its advantage over ZIFT is that it allows for the assessment of

fertilization and embryo quality.Success rate higher than ZIFT.

Sperm is injected directly into the eggs in a laboratory.Used if infertility originates from the male such as:

Low numbers of spermLow sperm motility

Single spermatozoan is directly injected into the cytoplasm of the oocyte through the micropuncture of zona pellucida.

INTRA CYTOPLASMIC SPERM INJECTION (ICSI)

ADVANTAGESCan be useful when very low numbers of motile sperm are

present and when there are problems with sperm binding and penetration.

DISADVANTAGESAltering the nature’s selection process for sperm can lead to

an increase risk of developmental and health issues for ICSI children, as well as a higher risk of miscarriage because of the poorer genetic material involved.

NEGETIVE ASPECTS OF ARTDue to administration of hormones and drugs, ovarian

hyperstimulation syndrome (OHSS) can occur.

Risks associated with pregnancyMultiple pregnancyIncreased risk of premature labor etc..

Can cause premature menopause.

Increased risk of ovarian cancer, atleast by 3 times when compared to normal women.

CONCLUSION

ART has been the answer for many childless couples, resulting in successful pregnancies and childbirth.

Today there is a range of infertile treatment that aims to ensure a healthy sustainable pregnancy.

But there are still risks, stress and high cost associated with ART.

With the advent of new technologies, it is hoped that these shortcomings would be overcome in the near future and every infertile couple would have the previlage of parethood.

RECENT TRENDSInnovative design of IVF equipment (PLoS ONE, june 2012)

A novel system for processing embryos during IVF treatment has been shown to significantly improve the chances of pregnancy by 27%.

Pioneered by a Newcastle team of fertility experts within the University and NHS, the innovative design of interlinked incubators provides a totally enclosed and controlled environment within which every step of the IVF process can be performed. 

BIBLIOGRAPHYSatyanarayana U, Biotechnology (2010), 1st edition, Books and

allied (P) Ltd, Kolkata.

Joseph. C. Daniel, Methods in mammalian embryology, Ist edition, W.H Freeman and company, San Fransisco

www. sart. org/publications/details.aspx? Id = 1522

www.youtube.com/

http://www.ncl.ac.uk/press.office/press.release/item/increased-fertility-rate-for-ivf-patients-achieved-by-new-equipment-design