REPRODUCTIVE TECHNOLOGIES AND ITS APPLICATIONS
REPRODUCTIVE TECHNOLOGIES AND ITS APPLICATIONS
Reproductive technologies have undergone a rapid evolution from simple procedures like the first insemination of fresh donor semen to a point where we now have the ability to collect epididymal sperm for microinjection into oocytes; freeze, thaw, and transfer donor gametes and embryos; create pregnancies in menopausal women, and in the near future may be able to harvest and store eggs from ovarian biopsies.
MAJOR REPRODUCTIVE TECHNOLOGIES
IN VITRO FERTILIZATION (IVF):
- In Vitro Fertilization involves collection of healthy ovum and sperms from healthy mother and father respectively and their fusion under appropriate conditions in vitro.
- If fertilization occurs, the resulting embryo is transferred in to the woman’s uterus, where it will implant in the lining of the uterus and develop.
BASIC TECHNIQUE IN IVF
- First of all ovaries are stimulated by using fertility drugs to produce several mature eggs rather than a single egg.
- Then ultrasound probe is inserted through vagina and mature follicles are identified,
- Then a needle is guided through the vagina into the follicles.
- The eggs are removed from the follicles through the needle by a suction device.
- At last, in the laboratory, the sperms are separated from the seminal plasma, and the motile sperms are placed together with each retrieved egg in a separate dish containing IVF culture medium, where fertilization occurs.
- The embryos are drawn into a tube and deposited in the uterine cavity.
EMBRYO TRANSFER TECHNOLOGY:
- Embryo transfer is a procedure by which fertilized egg or young embryo is transferred from donor mother to recipient mother or from test tube (IVF) to the recipient mother.
- The best stage for transfer is 2-4 cell stage. Embryo transfer technology is used for rapid multiplication of genetically superior genotype.
- Cloning is the production of identical animals, plants or microorganisms from a single individual. A clone means exact copy or copies of a single parent. Clones, owing to their identical genetic make up exhibit little, if any genetic variation.
- Monozygotic identical twins are clones. “Dolly”, the sheep, was a clone. Dolly was produced from a single cell from her mother. She had exactly the same genetic characteristics as her mother, the single parent.
- Cloning of animals has been based on a technique known as “nuclear transfer”.
- The nucleus of the egg cell (containing the DNA) is removed in a test tube, and the nucleus from the organism to be “cloned” is inserted in its place (nuclear transfer). It is then implanted in the uterus to grow like other embryos.
The uses of cloning are wide, such as infertile couples may choose this method to reproduce and embryonic stem cells can be grown to produce organs or tissues to repair or replace damaged ones.
ARTIFICIAL WOMBS. | REPRODUCTIVE TECHNOLOGIES AND ITS APPLICATIONS
- Artificial wombs technique could be used to help premature or “sick” human babies to survive and help foetuses in the final stages of multiple pregnancies when the womb becomes so cramped.
- In this technique a foetus of about 17 weeks is placed in a tank filled with liquid to stimulate amniotic fluid. The temperature is kept at constant. A machine pumps nutrients and oxygen into the baby’s blood.
- This technique was successfully experienced on goat foetus in Japan.
- Artificial insemination is the artificial introduction of semen into the reproductive tract of a female.
- Semen collected from a male with desirable hereditary characters can be frozen and transported through long distances to fertilize females.
- The method is used for those females who wish to conceive when normal conception is not possible.
GAMETE INTRA-FALLOPIAN TRANSFER (GIFT) –
- GIFT begins with ovulation induction as in IVF followed by egg retrieval, insemination and gamete transfer.
- Sperms and eggs are mixed and injected into the fallopian tubes. The fertilization takes place there as it does naturally.
SURROGATE PARENT –
- An embryo may be carried by the egg donor (Surrogate) or by another woman (gestational carrier).
- In the latter case, the eggs are removed from the infertile woman, fertilized using IVF, and the resulting embryo is placed into the gestational carrier uterus.
APPLICATIONS OF NEW REPRODUCTIVE TECHNOLOGIES IN HUMANS
- Enhanced Fertility:
- New reproductive technologies are used to correct both male and female hormonal disorders leading to infertility.
- For example, pulsatile gonadotropin releasing hormone administered by a computerized pump may be used to correct hypothalamic, hypogonadism and infertility, both in males and females.
- Exogenous gonadotropins are used both to induce ovulation in anovulatory woman and to enhance the number of ovulated eggs in women undergoing superovulation.
- Superior Genotype
- Embryo transfer technology is used for rapid multiplication of genetically superior genotype.
- To maintain future fertility:
- The availability of this technology has allowed men to bank sperms prior to undergoing chemo or radiotherapy that might affect gametogenesis.
- The recent ability to harvest immature eggs from ovarian biopsies suggests that similar procedures may be possible for women who must undergo radiation or chemotherapy.
- Restore fertility by involvement of couple:
- Procedures that involve the infertile couples include reconstructive tubal surgery, IVF, GIFT, and intracytoplasmic sperm injection (ICS!).
- All these procedures rely on ultrasound-guided oocyte aspiration and assisted reproductive technologies for placement of gametes or embryos.
- Restore fertility by involvement of a Third Party:
- Donor sperms, eggs and embryos are all being offered when one partner of the affected couple is unable to provide healthy gametes.
- In premature loss of ovarian function:
- The ability to do hormonal priming of a recipient uterus in a woman who has undergone premature ovarian failure, and to transfer an embryo resulting from in vitro fertilization of a donor egg, has been a major breakthrough for couples in whom there has been premature loss of ovarian function.
- Minimize serious maternal and foetal risks:
- Donor sperms, eggs, and embryos have been employed to avoid transmission of serious genetic disorders.
- Sex pre-selection may be useful to avoid certain types of sex linked genetic disorders such as muscular dystrophy and haemophilia.
The past two decades have seen a dramatic evolution and revolution in availability, access to and utilization of new reproductive technologies.
Physicians, the public, and society are now faced with difficult decisions about what ethical boundaries should apply to the available technologies.
Ethical principles are not static rather evolve as society evolves. Accordingly, continuing evaluation and re-evaluation of the individual and social benefits of new and emerging technologies will be essential, coupled with vigilance to monitor and avoid potential abuses of these new reproductive technologies. REPRODUCTIVE TECHNOLOGIES AND ITS APPLICATIONS