Placenta development is the first step in human embryo growth, scientists find

THE INITIATION of placenta development is the first step in the growth of human embryo following fertilisation, scientists have found.

Researchers have discovered that the first cell division in the fertilised egg, or zygote, kickstarts the development of the organ that provides oxygen and nutrients to a growing baby.

This happens days before the cells in the zygote – which divides repeatedly as it moves down the fallopian tube to the uterus – become specialised to do certain tasks within the body.

The researchers believe the findings, published in the journal Nature, could to lead to improvements in fertility treatments such as in- vitro fertilisation ( IVF) and help scientists understand more about placental- related diseases in pregnancy.

Dr Kathy Niakan is senior author and group leader of the

Human Embryo and Stem Cell Laboratory at the Francis Crick Institute.

She said: “This study highlights the critical importance of the placenta for healthy human development.

“If the molecular mechanism we discovered for this first decision in humans is not appropriately established, this will have significant negative consequences for the development of embryos and their ability to successfully implant in the womb.”

A team of scientists led by the Francis Crick Institute examined the biological pathways that were active in donated human embryos. These embryos were morulas – in the very early stages of development, consisting of around 16 to 32 cells.

The aim was to understand how cells become specialised in the early embryos.

The researchers observed that as cells begin to divide after fertilisation, some start to join together, which triggers “a cascade of molecular events” initiating the development of the trophectoderm – a layer of cells providing nutrients for the growing embryo which later becomes part of the placenta.