https://doi.org/10.1351/goldbook.11235
Group of cells in the amphibian embryo that is important in orientation of surrounding cells and facilitates development of the central nervous system.
Note: Cells on the ventral side of the Xenopus blastula secrete factors such as bone morphogenetic protein-4 (BMP-4) to signal the overlying ectoderm to become skin. The Spemann organizer blocks the action of BMP-4 by secreting chordin and noggin, allowing the ectoderm to develop into the brain and spinal cord by default.