A type of cell that generates long structural proteins that link cells together.

After injury (including circumcision), fibroblast cells quicly create an extracellular matrix called Type I collagen.  Over time, these fibers transform into a much stronger Type III collagen, or commonly known as scar tissue. After circumcision, fibroblasts form connections between the remaining shaft skin and penile shaft, immobilizing the skin. Non-surgical restoration quickly breaks down these fibers, often causing inflammation, but giving an initial surge of mobility. 

Resources: Fibroblast - From Wikipedia