Insemination
After eggs are retrieved, they are transferred to the embryology laboratory where they are kept in conditions that support their needs and growth. The embryos are placed in small dishes or tubes containing "culture medium," which is special fluid developed to support development of the embryos made to resemble that found in the fallopian tube or uterus. The dishes containing the embryos are then placed in incubators, which control the temperature and atmospheric gasses the embryos experience.
A few hours after eggs are retrieved, sperm are placed in the culture medium with the eggs, or individual sperm are injected into each mature egg in a technique called Intracytoplasmic Sperm Injection (What is ICSI?). We inseminate all the mature eggs so that there will be an optimal chance of obtaining several healthy-appearing embryos. The day after the retrieval, the eggs are examined for presence of 2 circular structures within the eggs (pro-nuclei) which constitute evidence of normal fertilization.