Incubation and Fertilization: Fertilization and Embryo Formation takes place in incubator where they are nourished until they are ready for transfer (3-5 days). The IVF incubator is a highly controlled environment that maintains precise temperatures, gas concentrations, and uses highly filtered purified air. Fertilization is apparent in 24 hours, but complete embryo formation takes little longer. After a period of 16-20 hours, the eggs are examined and checked for the first signs of fertilization. At this time, the embryologist can observe under the microscope "two pronuclei".
The fertilized egg essentially looks like a "round ball with two eyes" and they represent the genetic material from the husband and wife. After two to three days, if the embryos are growing normally, they are ready for the IVF embryo transfer. We then observe the embryos for 3-6 days. At the present time, embryos can be transferred either 3 or six days following retrieval. A 3 day embryo is usually at the 6-8 cell stage. After 3 days blastocyst is transferred this improves implantation and pregnancy rates.
