The Spemann-Mangold organizer is a group of cells that are responsible for the induction of the neural tissues during development in amphibian embryos.
[1] This discovery significantly impacted the world of developmental biology and fundamentally changed the understanding of early development.
Prior to its discovery, it had been hypothesized by multiple groups that there exists a portion of the developing embryo that serves as an "organization center".
The Spemann-Mangold organizer refers to the population of cells in the Xenopus laevis embryo that establishes the dorso-ventral and antero-posterior axes.
The other two signals arise from the vegetal pole and induce the extreme ventral and dorsal mesoderm in the overlying marginal zone.
[6][5] Sia and Xtwn can function as homo- or heterodimers to bind a conserved P3 site within the proximal element (PE) of the goosecoid (Gsc) promoter.
[6] Wnt signaling also acts with mVegT to upregulate Xnr5, secreted from the Nieuwkoop center, in the interior dorso-vegetal region, which will then induce additional transcription factors such as Xnr1, Xnr2, Gsc, chordin (chd).
Following transcriptional activation by Sia and Xtwn, Gsc is expressed in a subset of cells encompassing 60° of arc on the dorsal marginal zone.
[9] This created a large international impact with labs in Japan, Russia, and Germany changing the way they viewed and studied developmental organization.
[9][10][11] However, due to the slow progress in the field, many labs move research interests away from the organizer, but not before the impact of the discovery was made.
At that time, many students who went abroad to study in American and European labs, came back with new ideas about approaches to developmental sciences.
Spemann initiated the movement of developmental and molecular biology and influenced many projects in Germany based on his findings.
Spemann's work with the minced organizer tissue indicated the presence of morphogens which then lead to the double gradient hypothesis of Toivonen and Saxén.
Because of the Spemann-Mangold organizer discovery and suggestion of morphogens, labs in Germany were able to further learn about the mechanisms behind development with new methods to further the knowledge in the field.