So a group of molecules that play a particularly important role in the process of morphogenesis are known as morphogens. So morphogens are these chemicals are these molecules that act as signal molecules and that can actually affect the behavior of the cell. For example, they can change the different types of processes that take place within the cell and they can actually cause that cell to migrate to move from one location to another location within that nearby developing tissue. Now, cells generally respond to morphogens based on the level or the concentration of that morphogen found in that local environment. And to see what we mean by that let's take a look at the following diagram. So we have cell number one and cell number two.