Oocyte fertilization is a critical step in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) programs, during which, in the embryology laboratory, a sperm fuses with the egg to form an embryo. The procedure is indicated for various forms of infertility, including blocked or dysfunctional fallopian tubes, poor sperm quality, or failed attempts at conception. Depending on the situation, embryologists either create conditions for natural cell fusion (IVF) or inject a single selected sperm directly into the egg (ICSI). The procedure enables the formation of viable embryos, which are then transferred into the uterine cavity to achieve a long-awaited pregnancy.