ICSI (Intra Cytoplasmic Sperm Injection): Direct Sperm Injection
Biology · Reproductive Health · NEET
ICSI (Intra Cytoplasmic Sperm Injection) is a specialised ART method in which a single sperm is injected directly into the ovum (egg) in the laboratory to form an embryo. It is an in-vitro (outside the body) technique, mainly used when the sperm count is very low. Memory hook: "ICSI = I Choose one Sperm and Inject it" straight into the egg.
In ICSI, a single selected sperm is drawn into a fine micro-needle and injected directly into the cytoplasm of the ovum in the laboratory (in-vitro). The embryo that forms is later placed back using ET, ZIFT or IUT. This is why ICSI is classed as an in-vitro, not in-vivo, technique.
Your doubts, answered
Is ICSI an in-vivo or in-vitro technique?
ICSI is in-vitro. The sperm is injected into the ovum in the laboratory, so the embryo forms outside the body. NEET has directly tested this: a statement calling ICSI an 'in-vivo' procedure is INCORRECT. Remember: any technique where fertilisation happens in the lab (IVF, ICSI) is in-vitro.
How is ICSI different from IVF?
In IVF, many sperms are placed near the ovum in a dish and one sperm fertilises the egg on its own. In ICSI, one selected sperm is picked up in a fine needle and injected directly inside the ovum. So ICSI is used when the sperm cannot reach or penetrate the egg by itself (for example, very low count or poor motility). Both form the embryo in the lab (both in-vitro).
Is ICSI the NCERT answer for very low sperm count?
Be careful. ICSI does help with low sperm count, but NCERT's stated remedy for 'inability to inseminate' or 'very low sperm count' is Artificial Insemination (AI). In the NEET 2017 PYQ on low sperm count, the official key was AI, not ICSI. So match the answer to NCERT's exact wording, not just to logic.
What exactly happens to the sperm in ICSI?
A single sperm is directly injected into the cytoplasm of the ovum. This is what the name says: Intra Cytoplasmic (inside the cytoplasm) Sperm Injection. The resulting embryo is then transferred by ET, ZIFT or IUT depending on its stage.
Does ICSI transfer an embryo like ZIFT or IUT?
No. ICSI is a fertilisation (embryo-forming) technique, not a transfer technique. Transfer of an embryo is done by ZIFT (early embryo into fallopian tube) or IUT (embryo with more than 8 blastomeres into uterus). NEET 2020 tested that only ZIFT and IUT transfer embryos, while ICSI and GIFT do not.
⚠️ The NEET trap ✗ ICSI is an in-vivo procedure because the sperm is injected into the ovum. ✓ ICSI is in-vitro: the sperm is injected into the ovum in the laboratory and the embryo forms outside the body. 🧠 Injection does NOT mean inside the body. In ICSI the injection happens in the lab dish, so it is in-vitro. NEET 2023 marked the 'in-vivo' statement as incorrect.
Real NEET questions
NEET 2023 Phase 2
Given below are two statements: Statement I: Intra Cytoplasmic Sperm Injection (ICSI) is another specialised procedure of in-vivo fertilisation. Statement II: Infertility cases due to inability of the male partner to inseminate female can be corrected by artificial insemination (AI). In the light of the above statements, choose the correct answer.
A · Both Statement I and Statement II are true
B · Both Statement I and Statement II are false
C · Statement I is correct but Statement II is false
D · Statement I is incorrect but Statement II is true ✓
Solution: Statement I is incorrect: ICSI forms the embryo in the laboratory by injecting a sperm directly into the ovum, so it is in-vitro, not in-vivo. Statement II is correct: inability of the male to inseminate (or very low sperm count) is corrected by artificial insemination (AI). Hence Statement I incorrect, Statement II true.
ReNEET 2026
The method of directly injecting a sperm into the ovum in assisted reproductive technology is called:
A · Gamete intra fallopian transfer (GIFT)
B · Zygote intra fallopian transfer (ZIFT)
C · Intra cytoplasmic sperm injection (ICSI) ✓
D · Embryo transfer (ET)
Solution: ICSI is the in-vitro procedure in which a single sperm is directly injected into the ovum to form an embryo in the lab. GIFT transfers an ovum into the fallopian tube and ZIFT transfers an early zygote/embryo, so only ICSI matches 'directly injecting a sperm into the ovum'.
NEET 2020
In which of the following techniques, the embryos are transferred to assist those females who cannot conceive?
A · ICSI and ZIFT
B · GIFT and ICSI
C · ZIFT and IUT ✓
D · GIFT and ZIFT
Solution: ZIFT transfers the zygote/early embryo (up to 8 blastomeres) into the fallopian tube and IUT transfers embryos with more than 8 blastomeres into the uterus, so both move the embryo. ICSI injects a sperm into the ovum and GIFT transfers a gamete (ovum), so neither transfers an embryo. Hence ZIFT and IUT.
Solved Reproductive Health NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
ICSI stands for Intra Cytoplasmic Sperm Injection. It means injecting a sperm inside the cytoplasm of the ovum.
Is ICSI in-vivo or in-vitro?
ICSI is in-vitro. The embryo is formed in the laboratory, so it is an outside-the-body technique like IVF.
What is ICSI mainly used for?
It is used when the sperm cannot fertilise the egg on its own, for example with very low sperm count or poor sperm quality. A single good sperm is picked and injected into the ovum.
Does ICSI transfer an embryo?
No. ICSI only forms the embryo. Transfer of the embryo is done separately by ET, ZIFT (fallopian tube) or IUT (uterus).
What is the difference between ICSI and IVF?
In IVF the sperm fertilises the egg by itself in a dish; in ICSI one sperm is injected directly into the egg. Both are in-vitro (lab) methods.
