Researchers have created the world’s first “synthetic embryos” – a revolutionary achievement that bypassed the need for sperm, eggs and fertilization, writes The Guardian.

Scientists at the Weizmann Institute in Israel have discovered that mouse stem cells can be turned into early embryonic structures with an intestinal tract, the beginnings of a brain and a beating heart.

The living structures, known as synthetic embryos because they are created without fertilized eggs, are expected in the short term to help better understand how organs and tissues form during the development of natural embryos.

But the researchers believe the work could also reduce animal testing and ultimately open the way to new sources of cells and tissues for human transplants.

For example, skin cells from a leukemia patient can be turned into bone marrow stem cells to treat the patient’s disease.

“Remarkably, we have shown that embryonic stem cells generate whole synthetic embryos, meaning they include the placenta and the yolk sac that surrounds the embryo,” said Professor Jacob Hanna, who led the effort. “We are very excited about this work and its implications,” he added.

The work was published in Cell.

Last year, the same team described how they created a mechanical uterus that allowed natural mouse embryos to grow outside the uterus for days.

In the latest work, the same device was used to feed stem cells to a mouse for more than a week, almost halfway through the mouse’s gestation period.