In vitro fertilization. Surgeons removing a sample of follicular fluid from a woman's ovary during in vitro fertilization (IVF) treatment. The fluid is aspirated through a needle inserted into the abdomen. It contains mature eggs that have developed in the follicles of the woman's ovaries. In the next stage of the IVF process, the eggs will be fertilized with sperm and cultured until the resulting embryos are at an early developmental stage known as a blastocyst. The blastocysts will then be implanted into the woman's uterus, enabling pregnancy to proceed as normal. IVF treatment enables couples with a range of infertility problems to conceive.