How Does an Embryo Get Its Shape?
by Dr. Susan Daniel
When you look at an early embryo in the lab, it is amazing to think that in a few short weeks this ball of cells will become an elongated embryo with distinct parts.
The first clues to explain how this dramatic change in shape occurs came from the work of Han Spemann and Hilde Mangold in 1924. They discovered that amphibian embryos contain an 'organizer center'. When organizer cells from a newt tadpole were transplanted to another newt, they induced the cells in the area that they had been placed to form an embryonic structure that would not have formed otherwise. Spemann was awarded the Nobel Prize in 1935 for the discovery of organizers in early embryonic development.
Recently, scientists at the Hebrew University of Jerusalem reported that they have been able to generate human organizer cells from human embryonic stem cells. To show that these cells had organizer ability, they repeated Spemann and Mangold's experiments using frog embryos. Amazingly, the human organizer cells induced the formation of a neural tube (a tissue that becomes the embryo's central nervous system) composed of frog cells in the area into which the organizer cells had been injected.
"Hans Spemann - Biography". 20 July 2011. http://nobelprize.org/nobel_prizes/medicine/laureates/1935/spemann-bio.html
“Scientists show for the first time how early human embryo acquires its shape”. 19 July 2011.