Now, a chemical factor is simply a special type of chemical while a mechanical factor is simply a physical force that exists between our cells and these two factors basically play together. There is an interplay between these two factors that stimulates the process of morphogenesis. And as we'll see in just a moment these two different types of factors can basically influence the different types of processes that takes place within the cell and they can also influence the behavior of that cell. 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.