Intra Cytoplasmic Sperm Injection
கருமுட்டைக்குள் விந்தணு செலுத்துதல்
Nature does not always guarantee fertilization even when gametes are present. When male factor infertility renders natural penetration impossible, we bypass the biological barrier entirely. ICSI is not a luxury; it is a surgical intervention at the cellular level.
The idea
Intra Cytoplasmic Sperm Injection (ICSI) is a specialized ART procedure. A single sperm is directly injected into the cytoplasm of the ovum in a laboratory setting. This technique is used to form an embryo when standard IVF fails to achieve fertilization. It bypasses the need for the sperm to penetrate the zona pellucida naturally.
Why it matters
It is used to overcome male infertility issues where sperm count or motility is too low to achieve natural fertilization.
NEET lens
NEET focuses on the distinction between IVF and ICSI. Remember: ICSI is specifically for direct injection into the cytoplasm. Do not confuse it with ZIFT or GIFT. Memorize that this is an 'in vitro' procedure used when male gametes cannot fertilize the ovum on their own.
Clinical significance
ICSI is the definitive treatment for severe male factor infertility, such as oligospermia or asthenozoospermia. Without this, these patients would remain biologically infertile. It effectively bypasses defects in sperm motility and acrosomal reaction.
Introduction
ICSI (Intra-Cytoplasmic Sperm Injection) is an ART procedure in which a single sperm is injected directly into the cytoplasm of a mature oocyte using a glass micropipette, used primarily for severe male factor infertility.
Core concept
Procedure: Ovarian stimulation + egg retrieval (same as IVF). Mature oocyte identified. Using micromanipulator: holding pipette stabilizes oocyte. Injection pipette (fine glass needle) picks up single sperm → penetrates zona pellucida + cell membrane → deposits sperm into oocyte cytoplasm. Fertilization assessed 16-18 hours later (2 pronuclei visible = fertilized). Embryo culture + transfer = same as standard IVF. Indications: Severe oligospermia (very few sperm). Azoospermia (no sperm) — sperm retrieved surgically (TESA: testicular sperm aspiration; TESE: testicular sperm extraction). Previous failed fertilization with conventional IVF. Antisperm antibodies. Poor sperm morphology. Frozen sperm (poor survival after thaw). Success: fertilization rates 70-80% per injected egg. Pregnancy rates similar to standard IVF when female factors absent.
Go deeper
Surgical sperm retrieval for azoospermia: Obstructive azoospermia (sperm produced but blocked): PESA (percutaneous epididymal sperm aspiration) or MESA (microsurgical) — high quality sperm. Non-obstructive azoospermia (testicular failure): TESE (testicular sperm extraction) — small testicular biopsy to search for rare sperm. Even men with Klinefelter syndrome (47,XXY) may have rare sperm in testes → TESE + ICSI → biological fatherhood possible.
From Class 10
ICSI is a procedure where a single sperm is injected directly into an egg — designed for cases of severe male infertility where sperm cannot fertilize the egg on their own.