Researchers have discovered that after fertilisation, the very first step in human development is the initiation of placenta creation, an organ responsible for providing oxygen and nutrients to a growing baby.
They say the findings, published in the journal Nature, could also help scientists understand more about the diseases that affect the placenta during pregnancy.
Dr Kathy Niakan, senior author and group leader of the Human Embryo and Stem Cell Laboratory at the Francis Crick Institute in London, said: “This study highlights the critical importance of the placenta for healthy human development.”
Understanding the process of early human development could provide us, or others, with insights that may lead to improvements in IVF success rates in the future
She added: “Understanding the process of early human development could provide us, or others, with insights that may lead to improvements in IVF (in vitro fertilisation) success rates in the future.
“It could also allow us to understand early placental dysfunctions that can pose a risk to human health later in pregnancy.”
A team of scientists led by the Francis Crick Institute examined the biological mechanisms in donated human embryos.
These embryos were in the very early stages of development, consisting of around 16-32 cells.
The aim was to understand more about cell specialisation – a key process in embryo development where cells are assigned to do specific tasks.
The researchers observed that as cells begin to divide after fertilisation, some start to join together, triggering “a cascade of molecular events” that initiates the development of the placenta.
These cells change shape to form placental progenitor cells, which help the embryo implant in the womb.
The team then investigated this developmental step in mouse and cow embryos.
They found that while the mechanisms differ between species in the latest stages of embryo development, the first cell decision still initiates placenta creation.
The researchers say this “valuable insight into early development” could lead to improvements in fertility treatments in the future.
Dr Niakan said: “During IVF, one of the most significant predictors of an embryo implanting in the womb is the appearance of placental progenitor cells under the microscope.
“If researchers could identify better markers of placental health or ways to improve it, this could make a difference for people struggling to conceive.”
