Supplementary information

Supplementary information S1 (movie)

Re-enactment of the Spemann–Mangold experiment by Eddy De Robertis.

The movie starts with photos of Hans Spemann and Hilde Mangold circa 1924 (Ref. 1). Next, it shows the author at the dissection microscope. Two embryos can be seen, one of which has the dorsal blastopore lip, the Spemann's organizer, clearly visible as a crescent. With the help of a tungsten needle and forceps, a square of organizer tissue is excised — the operation is done free-hand. The organizer is pushed into the ventral side of a recipient gastrula with an eyebrow hair. One hour after transplantation, the graft has, almost miraculously, healed into the host embryo. Two days later, a Siamese twin has developed with two perfect body axes. The Spemann's organizer graft induced complete central nervous systems and mesodermal somites in tissues of the host that would otherwise have become ventral tissue.

Reference

1. De Robertis, E. M. & Aréchaga, J. (eds). Special issue: the Spemann–Mangold Organizer Int. J. Dev. Biol.45, (2001).

Supplementary information S1 (movie) - Download Movie (12KB)