XB-ART-20690Nature October 6, 1994; 371 (6497): 487-92.
Activin signalling and response to a morphogen gradient.
Using combinations of amphibian embryo tissues, it is shown that the selection of genes expressed by a cell is determined by its distance from a source of activin, a peptide growth factor contained in vegetal cells and able to induce other cells to form mesoderm. This long-range signal spreads over at least 10 cell diameters in a few hours. It does so by passive diffusion, because it can by-pass cells that do not themselves respond to the signal nor synthesize protein. These results provide direct support for the operation of a morphogen concentration gradient in vertebrate development.
PubMed ID: 7935761
Article link: Nature