When the embryologists keep the embryos in culture in the laboratory this culture must fulfill some conditions. The temperature of it must always be safe, at a constant temperature of 37 Celsius degrees. The culture media must have a determined osmolarity and pH. The humidity must be high – to create this they oil with the culture media to avoid the evaporation of this medium. An embryo incubator has two simulate the maternal environment of the uterus and that’s the reason why it must fulfill these conditions. All kinds of incubators in our days fulfill these conditions but we can talk about many different types of incubators. When using the traditional ones, to be able to assess the development of the embryo embryologists must open the door of this incubator, take the plate where the embryo is, remove it and access the embryo. On the other hand, we have the Time-lapse system where we use a traditional incubator but we don’t do the step of opening the door, moving the plate with the embryo which can destroy the ideal conditions that is needed for the development. With the Time-lapse system, as we are going to see now, it doesn’t happen.