Final answer:
Fusion's major obstacle is the Coulomb repulsion between positively charged nuclei, and overcoming this requires enough kinetic energy. Similarly, cellular fusion involves stabilizing focal adhesions through forces applied by a sufficiently stiff substrate.
Step-by-step explanation:
The primary cause of retromer dissociation for fusion relates to the Coulomb repulsion between nuclei. This electrostatic repulsion due to like positive charges is the major obstruction that must be overcome to allow nuclei to come close enough for fusion to occur. The attractive nuclear force is short-ranged and thus, the nuclei must have enough kinetic energy to overcome the electric potential energy barrier—a concept analogous to rolling a ball over a hill to fall into a deeper well.
When considering fusion within a cellular context, focal adhesions and the physical forces exerted by contractile stress fibers, as well as the forces resulting from retrograde flow, play crucial roles. These forces are necessary to stabilize adhesions. Without sufficient force, typically provided by a substrate of a certain stiffness, the adhesion cannot be maintained, leading to decay rather than growth and maturation.