An adequate number of spermatozoa are added to the dish containing the egg in laboratory. Only one spermatozoon will fuse with an egg; it is called “fertilization”.
In cases of severe male infertility, the sperm may not be able to penetrate the eggshell and fertilize the egg. At this situation, the procedure of “intra-cytoplasmic sperm injection (ICSI)” will be applied.
Each egg is picked up by a holding pipette and then is injected with an immobilized spermatozoon.
Fertilization by ICSI is more efficient than a traditional insemination in which an adequate number of spermatozoa are added to a dish containing the egg.
Generally more than 90% of egg can be fertilized via the procedure of ICSI. It is an excellent technique to achieve fertilization in case where conventional insemination would not be successful.