Here you shall find a clarification of the different stages of fetal growth, from the very first stage, called zygote, to the last phase, in which it is known as fetus. It will be called this way up until childbirth.
When an egg is released and then fertilised by sperm, the most amazing event in life occurs: pregnancy. The development of the baby consists of several different stages throughout the nine months of gestation.
It’s hard to choose what to do with leftover embryos in reproductive treatments. One option is to donate them to other couples.
Some assisted reproductive techniques, such as in vitro fertilisation (IVF) or ICSI, perform egg fertilisation outside the woman’s body. For this reason, embryo culture is necessary up to the day in which the embryo transfer is performed.
Blastocyst is the stage in which embryo implantation within the uterus occurs naturally. To reach this stage, the embryo is cultured up to day 5-6 by means of a sequential culture system.
Embryos can be classified in 4 categories –from A to D– ranging from best quality to least developed embryos. This classification is mainly visual and rather subjective, but there are also several studies to identify their metabolic activity.