Embryo development is a complicated process that we see the initial parts of during the IVF process in the laboratory.
So the first step is that the sperm needs to fertilise the egg and that occurs either by mixing the egg and sperm or by a procedure called ICSI, where the sperm is injected inside the egg. The embryo, the egg and sperm DNA, then fuse to form what’s called pronuclei, and the scientists can look at those pronuclei to tell whether successful fertilisation of the embryo has occurred.
The embryos then go on to divide, so initially two cells, four cells, eight cells, and beyond. And those initial stages can be looked at to ensure that they are a normally developing embryo. After around about four to five days the embryo starts to form what’s called a blastocyst, and that means the embryo has separated into embryo cells or the inner cell mass on the inside, and cells called the trophectoderm which are on the outside of the embryo.
By that stage, the embryo is around about a hundred cells and that’s usually when we implant an embryo inside the uterus.
Beyond that there’s a very complicated process of further development getting from an embryo towards a healthy baby.
Dr Katrina Rowan is a fertility specialist, reproductive endocrinologist and reproductive surgeon with consulting rooms in the heart of Sydney’s CBD. Katrina prides herself in her ability to guide and educate her patients. With her support, patients feel comfortable and deepen their understanding of their own unique fertility situation.https://monashivf.com/specialists/dr-katrina-rowan/