In a groundbreaking advance that bypassed the need for sperm, eggs and fertilisation, scientists have created synthetic human embryos using stem cells. The synthetic embryos develop to a stage equivalent to that of natural embryos about 14 days after fertilisation.

The Synthetic model do not have a beating heart or the beginnings of a brain, but include cells that would typically go on to form the placenta, yolk sac and the embryo itself. The model structures, each grown from a single embryonic stem cell, reached the beginning of a developmental milestone known as gastrulation, when the embryo transforms from being a continuous sheet of cells to forming distinct cell lines and setting up the basic axes of the body. At this stage, the embryo does not yet have a beating heart, gut or beginnings of a brain, but the model showed the presence of primordial cells that are the precursor cells of egg and sperm.

TheSynthetic model human embryos could help in study the earliest stages of human development. It could spurs further research into genetic disorder. The synthetic embryo holds the promise of shedding light on what is called the ‘black box’ period of the development of the foetus — the period before a pregnancy’s progress can be detected on a scan.

Scientists say these model embryos, which resemble those in the earliest stages of human development, could provide a crucial window on the impact of genetic disorders and the biological causes of recurrent miscarriage.

It could provide opportunities to study human embryonic development at later stages than ever before. But they also raise ethical and legal questions about the status of such ‘embryo models’ and how they should be regulated.

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Stem cells are, unspecialized cells of the human body that are able to develop into many different cell types. This can range from muscle cells to brain cells. In some cases, they can also fix damaged tissues. Stem cells are They are able to differentiate into any cell of an organism and have the ability of self-renewal. Stem cells exist both in embryos and adult cells.

Stem cells are divided into 2 main forms. They are embryonic stem cells and adult stem cells.

Embryonic stem cells. The embryonic stem cells used in research today come from unused embryos. These result from an in vitro fertilization procedure. They are donated to science. These embryonic stem cells are pluripotent. This means that they can turn into more than one type of cell.

Adult stem cells. There are 2 types of adult stem cells. One type comes from fully developed tissues such as the brain, skin, and bone marrow. There are only small numbers of stem cells in these tissues. They are more likely to generate only certain types of cells. For example, a stem cell that comes from the liver will only make more liver cells.

The second type is induced pluripotent stem cells. These are adult stem cells that have been changed in a lab to be more like embryonic stem cells.