Olfactory receptor neurons select which odor receptors to express

It may appear difficult to reconcile the fact that almost every cell in the body of an animal has an identical dose of genes with the variety of different appearances and properties cells can display—bone, skin, hair, muscle, and many more. This may seem even more complex given that all of these tissue types derive originally from a single fertilized egg cell. Understanding the many regulatory mechanisms that create different cells from a single template is the work of developmental biology.