Retinoic acid gradient visualized for the first time in an embryo
Researchers from the RIKEN Brain Science Institute in Japan report a new technique that allows them to visualize the distribution of retinoic acid in a live zebrafish embryo, in real-time. This technique enabled them to observe two concentration gradients going in opposing directions along the head-to-tail axis of the embryo, thus providing long-awaited evidence that retinoic acid is a morphogen.
A morphogen is a substance governing the pattern of tissue development in the process of morphogenesis, and the positions of the various specialized cell types within a tissue.
Since morphogens diffuse through the tissues of an embryo during early development, concentration gradients are set up. These gradients drive the process of differentiation of unspecialised (stem) cells into different cell types, ultimately forming all the tissues and organs of the body.