Some newly reported clumps of cells growing in lab dishes have been hailed as the closest things to human embryos that scientists have ever made in the lab.
These entities are human embryo models — masses of cells created from stem cells that mimic some properties of certain stages of embryo development. The achievement gives researchers a chance to look at human development beyond the first week or so, when an embryo must implant in the uterus to develop further. That post-implantation stage hadn’t been re-created in lab dishes — until now.
For years, scientists have studied the first week or so of human development using donated human embryos or embryo models. From those, researchers learned a great deal about the formation of the ball of cells known as a blastocyst. Blastocysts have an outer layer of cells that will form the placenta and other support systems for the developing embryo, and an inner cluster of cells that will give rise to the body.
But it’s the next few weeks of life when the real action happens, says stem cell biologist and embryologist Jacob Hanna of the Weizmann Institute of Science in Rehovot, Israel.
