In standard IVF, fertilisation takes place when a prepared sperm suspension is introduced to denuded oocytes in a culture dish and left for a defined incubation period, during which one sperm penetrates the zona pellucida and fuses with the oolemma naturally. The process relies on sperm motility, zona penetration capacity, and oolemma fusion — all of which require adequate sperm quality, count, and function.
ICSI (intracytoplasmic sperm injection) bypasses this natural process entirely. A single spermatozoon is selected under high-power microscope magnification, immobilised, and injected directly into the ooplasm using a fine angled-cut injection pipette on a micromanipulation stage. The oocyte is held in position by a holding pipette applying negative pressure to the zona. ICSI is used when sperm quality, concentration, or motility is insufficient for reliable natural fertilisation; when previous IVF cycles have had poor or failed fertilisation; or when surgically retrieved sperm from TESA, PESA, or MESA procedures is being used.
The ICSI injection pipette geometry matters significantly for clinical outcomes. Tip diameter, wall thickness, and bevel angle determine whether the oolemma is punctured cleanly with minimal cytoplasmic disruption, or deformed excessively before penetration. Cryolab supplies ICSI injection pipettes and the full range of IVF micro pipettes. Contact Cryolab for specification guidance.
