Injecting sperms into the ovum is called the microinjection (intracytoplasmic sperm injection, ICSI). In test tube baby treatment process, the ovaries are stimulated by drugs to enable development of eggs then the eggs are collected and stored in special mediums (culture medium) in the laboratory for a certain period of time. Just before microinjection process, the cluster of cells surrounding the eggs is removed by a process called “peeling” then the mature eggs are identified.
Sperms derived by ejaculation or other surgical methods (TESA, TESE, Micro TESE) are processed with ‘sperm preparation’ techniques to separate the quality ones.
With microinjection method, a living sperm is inserted into an egg using special tools called micromanipulator and then stored in specific environments called incubator which mimics a mother’s uterus. So, the sperm is inserted into an egg. Unlike classical IVF, the possibility that the egg is fertilized, in other words, an egg and a sperm would join is higher through microinjection method since the sperm needs not to find the egg by itself.
On the following day after microinjection process, viewing two pronucleuses (nucleus) in the egg means that the egg has been fertilized. One of the nucleuses originates from the mother while the other originates from the father. 40-70% of mature eggs appear to be fertilized. This percentage can decrease depending on the quality of sperm or egg. Sometimes no fertilization may be viewed.