Q.Expand and explain the following techniques used in the 'Test Tube Baby' programme :
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Start your 14-day free trial to unlock the full solution →These techniques are part of Assisted Reproductive Technology (ART) to aid conception: GIFT involves transferring gametes (sperm and egg) into the fallopian tube for in vivo fertilization; ZIFT involves transferring in vitro fertilized zygotes into the fallopian tube; and IUI involves placing processed sperm directly into the uterus for natural fertilization.
The term 'Test Tube Baby' program broadly refers to Assisted Reproductive Technology (ART), which encompasses various medical procedures designed to help couples overcome infertility. These techniques manipulate gametes (sperm and eggs) or embryos outside the body to facilitate conception. While In Vitro Fertilization (IVF) is the most well-known ART, several other methods are employed depending on the specific cause of infertility.
Let's explore three such techniques: GIFT, ZIFT, and IUI.
(a) GIFT (Gamete Intrafallopian Transfer)
Concept and Intuition:
GIFT is a technique that aims to mimic natural fertilization as closely as possible. The core idea is to collect both the woman's eggs and the man's sperm, mix them, and then immediately place this mixture directly into the woman's fallopian tube. The hope is that fertilization will occur naturally within the fallopian tube, just as it would in a spontaneous conception, and the resulting embryo will then travel to the uterus for implantation. This approach is chosen when the fallopian tubes are healthy, but there's a barrier preventing the sperm and egg from meeting.
Procedure:
- Ovarian Stimulation: The woman is given fertility medications to stimulate her ovaries to produce multiple mature eggs, rather than just one, increasing the chances of success.
- Egg Retrieval: Once the eggs are mature, they are retrieved from the woman's ovaries using a minor surgical procedure, typically guided by ultrasound.
- Sperm Collection: A semen sample is collected from the male partner, and the sperm are processed to select the most motile and healthy ones.
- Gamete Transfer: The retrieved eggs and the prepared sperm are mixed together and then immediately transferred into one or both of the woman's fallopian tubes using a thin catheter, usually performed via laparoscopy (a minimally invasive surgical procedure).
- Natural Fertilization: Fertilization is expected to occur naturally inside the fallopian tube. The resulting embryo then travels down the fallopian tube to the uterus for implantation.
When it's used:
GIFT is typically considered for couples with unexplained infertility, mild male factor infertility, or ovulation disorders, provided the woman has at least one healthy, functional fallopian tube. It is less common now due to the higher success rates and less invasive nature of IVF.
(b) ZIFT (Zygote Intrafallopian Transfer)
Concept and Intuition:
ZIFT is a hybrid technique that combines aspects of IVF with fallopian tube transfer. Unlike GIFT, where fertilization occurs inside the body, ZIFT ensures that fertilization has already taken place outside the body (in vitro) before the early embryo is transferred. The fertilized egg, now a zygote, is then placed into the fallopian tube. This approach guarantees that fertilization has occurred, while still allowing the early embryonic development to begin in the natural environment of the fallopian tube.
Procedure:
- Ovarian Stimulation and Egg Retrieval: Similar to GIFT and IVF, the woman undergoes ovarian stimulation, and mature eggs are retrieved from her ovaries.
- Sperm Collection: A semen sample is collected from the male partner, and sperm are prepared.
- In Vitro Fertilization (IVF): The retrieved eggs are fertilized with the prepared sperm in a laboratory dish. This step confirms that fertilization has successfully occurred.
- Zygote Transfer: After 24-48 hours, the fertilized eggs (now called zygotes) are transferred into the woman's fallopian tube(s) using a catheter, typically via laparoscopy.
- Embryo Development and Implantation: The zygote continues its development into an embryo within the fallopian tube and then travels to the uterus for implantation.
The key distinction between GIFT and ZIFT lies in the timing and location of fertilization:
- In GIFT, gametes (sperm and egg) are transferred, and fertilization occurs in vivo (inside the body).
- In ZIFT, zygotes (fertilized eggs) are transferred, meaning fertilization has already occurred in vitro (outside the body).
When it's used:
ZIFT is chosen when there is a need to confirm fertilization has occurred before transfer, or when there are concerns about the ability of gametes to fertilize within the fallopian tube (as might be the case in GIFT). It offers the advantage of confirmed fertilization while still allowing the early embryo to develop in the fallopian tube, which some believe provides a more natural environment than direct uterine transfer. …
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