What is “in vitro fertilization”? In vitro fertilization, embryo transfer and single sperm oocyte intracytoplasmic injection are commonly known as “IVF”. It is a technique in which the couple collects eggs and sperm separately, inseminates them in vitro, forms embryos, and then selects high-quality embryos for transfer to the uterus. How are the oocyte and sperm fertilized outside of the body? There are two types of fertilization methods in common use today: 1. Conventional fertilization: Natural human fertilization requires sperm and oocytes to meet in the fallopian tube, where they combine to form a fertilized egg; the conventional fertilization method of IVF simulates the natural human fertilization process by mixing the removed oocytes with the treated semen in a certain ratio and placing them in a Petri dish. The sperm will enter the oocyte and fuse with the oocyte to complete the fertilization process. 2.Single sperm microinjection: It is believed that a single sperm with good vitality and normal morphology is selected and injected directly into the oocyte through microscopic operation technique to help complete the fertilization process. It is suitable for patients with male factor infertility.