Scientists form human cell clumps that act like early-stage embryos

Cultured stem cells turn into blastoid balls', like natural blastocysts after egg fertilisation

Scientists have made clumps of human tissue that behave like early-stage embryos, a feat that promises to transform research into the first tentative steps of human development.

The clumps of cells, named blastoids, are less than a millimetre across and resemble structures called blastocysts, which form within a few days of an egg being fertilised. Typically blastocysts contain about 100 cells, which give rise to every tissue in the body.