Q.The method of directly injecting a sperm into ovum in Assisted Reproductive Technology is called:
The technique of directly injecting a single sperm into an ovum is called Intracytoplasmic Sperm Injection (ICSI).
In Assisted Reproductive Technology (ART), several procedures have been developed to help couples who face infertility. The key difference among these methods lies in where and how the sperm meets the egg. Some techniques bring sperm and egg together in a lab dish and let fertilisation happen naturally; others go a step further and physically place the sperm inside the egg.
The method described in the question — directly injecting a sperm into the ovum — is the most precise form of assisted fertilisation. It is used when the sperm count is very low, or when the sperm are unable to penetrate the egg on their own. In this procedure, a single sperm is picked up with a fine glass needle and injected straight into the cytoplasm of the egg. This bypasses all natural barriers and ensures that fertilisation can occur.
The NCERT textbook specifically mentions ICSI as the technique where "a sperm is directly injected into the ovum." This is a clear, exam-relevant distinction.
Let us look at the other options to understand why they are not correct:
- GIFT (Gamete Intra-Fallopian Transfer) — Here, both sperm and egg are placed together into the fallopian tube, but fertilisation happens inside the woman's body, not in a lab dish. There is no direct injection of sperm into the egg.
- ZIFT (Zygote Intra-Fallopian Transfer) — In this method, the egg is fertilised in the lab (usually by standard IVF), and the resulting zygote is transferred into the fallopian tube. Again, no direct injection is involved.
- ET (Embryo Transfer) — This is the final step in many ART procedures, where an embryo (already formed) is placed into the uterus. It does not involve any manipulation of sperm or egg at the fertilisation stage.
ICSI is a specialised form of IVF. While standard IVF lets sperm and egg meet in a culture dish, ICSI forces the entry by injection. Both are in vitro (outside the body) techniques, but only ICSI involves direct injection into the ovum.
The NCERT textbook for Class 12 Biology (Chapter 4: Reproductive Health) clearly lists ICSI under assisted reproductive technologies and describes it as the method where "a sperm is directly injected into the ovum." This is the exact wording used in the question, making the answer unambiguous.
In short, the method of directly injecting a sperm into an ovum is called Intracytoplasmic Sperm Injection (ICSI), which corresponds to option (C).
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