Question
Explain the procedures of IVF (In Vitro Fertilisation) and ICSI (Intracytoplasmic Sperm Injection). How do they differ from each other? When is each technique preferred? What is the difference between a “test tube baby” and a baby conceived naturally?
(NEET 2023, similar pattern)
Solution — Step by Step
IVF (In Vitro Fertilisation) literally means “fertilisation in glass.” The steps are:
- Ovarian stimulation: The woman is given hormones (FSH, LH) to produce multiple eggs instead of the usual one per cycle
- Egg retrieval: Mature eggs are collected from ovaries using ultrasound-guided aspiration
- Fertilisation: Eggs and sperm are mixed in a culture dish (petri dish, not a test tube). Sperm fertilises the egg naturally in the dish
- Embryo culture: The fertilised egg (zygote) is allowed to develop for 3-5 days to the 8-32 cell stage (morula/blastocyst)
- Embryo transfer (ET): The embryo is transferred into the woman’s uterus for implantation
If transfer occurs at the 8-cell stage into the fallopian tube, it’s called ZIFT (Zygote Intra-Fallopian Transfer). If at a later stage into the uterus, it’s called IUT (Intra-Uterine Transfer).
ICSI (Intracytoplasmic Sperm Injection) is a modification of IVF used when the male has very low sperm count or poor sperm motility.
In standard IVF, sperm must find and penetrate the egg on its own. In ICSI, a single sperm is directly injected into the egg using a fine glass micropipette under a microscope.
Everything else — ovarian stimulation, egg retrieval, embryo culture, and transfer — remains the same as in standard IVF.
| Feature | IVF | ICSI |
|---|---|---|
| Fertilisation method | Sperm + egg mixed; sperm penetrates naturally | Single sperm injected directly into egg |
| Sperm requirement | ~50,000-100,000 sperm per egg | Just 1 sperm per egg |
| Preferred when | Female factor infertility (blocked tubes, endometriosis) | Male factor infertility (low count, poor motility) |
| Cost | Lower | Higher (requires micromanipulation equipment) |
| Success rate | 40-50% per cycle | Similar to IVF once fertilisation occurs |
The term “test tube baby” is a misnomer — fertilisation happens in a petri dish, not a test tube. More importantly, the baby develops in the mother’s womb just like any naturally conceived baby. Only the first few days of development (fertilisation and early cell division) happen outside the body.
The baby is genetically identical to one conceived naturally — same parents, same chromosomes. There is no genetic difference between IVF and natural conception babies. Louise Brown (1978, UK) was the first IVF baby; Kanupriya Agarwal (1978, India — Dr Subhash Mukhopadhyay) was among the first in India.
Why This Works
IVF bypasses the natural barriers to fertilisation. If fallopian tubes are blocked (preventing egg and sperm from meeting), IVF takes the meeting to a lab dish. If sperm can’t penetrate the egg (due to low motility or count), ICSI physically delivers the sperm inside.
The key insight: these techniques don’t create anything artificial. They simply provide the right conditions for natural biological processes (fertilisation, cell division) to occur when the body’s own systems can’t manage it.
Alternative Method
For exam recall, remember the ARTs in order of intervention:
- IUI (Intra-Uterine Insemination): Sperm placed directly in uterus (least invasive)
- IVF: Fertilisation outside body, embryo transferred to uterus
- ICSI: Sperm injected into egg (most technically demanding)
- GIFT (Gamete Intra-Fallopian Transfer): Unfertilised egg + sperm placed in fallopian tube
NEET frequently asks: “ZIFT stands for?” — Zygote Intra-Fallopian Transfer. “In ICSI, what is injected?” — A single sperm into the cytoplasm of the egg. “First test tube baby in India?” — This varies by source; NCERT focuses on the concept, not names. Focus on the procedure differences between IVF, ZIFT, GIFT, and IUI.
Common Mistake
Students write that “the baby develops in a test tube” in IVF. This is completely wrong. Only fertilisation and early embryo development (3-5 days) happen outside the body. The embryo is then transferred to the mother’s uterus where it implants and develops normally for 9 months. The baby is delivered naturally or via C-section, just like any other baby.