Well, the major difference between the intrinsic and the extrinsic pathway is the origin in the extrinsic pathway is outside of the cell. So in this mechanism, the signal molecules are originating outside of the cell. And they stimulate that cell to commit suicide inside that cell. So it begins on the outside, but then it takes place. Apatosis takes place on the inside. So healthy cells contain special integral membrane proteins known as deaf receptors and that can bind complementary molecules known as deaf activators.