What is repair by scar formation? What are the steps?

If repair cannot be accomplished by regeneration alone, it occurs by replacement of the injured cells with connective tissue, leading to the formation of a scar, or by a combination of regeneration of some residual cells and scar formation.

Steps involved in repair in scar formation:

• Clot formation
• Inflammation
• Angiogenesis and formation of granulation tissue, 
• Migration and proliferation of fibroblasts, 
• Collagen synthesis, 
• Connective tissue remodeling.
  

Repair by regeneration

• Different tissues consist of continuously dividing cells (epithelia, hematopoietic tissues), normally quiescent cells that are capable of proliferation (most parenchymal organs), and nondividing cells (neurons, skeletal and cardiac muscle). The regenerative capacity of a tissue depends on the proliferative
  potential of its constituent cells.
• Cell proliferation is controlled by the cell cycle, and is stimulated by growth factors and interactions of cells with the extracellular matrix.
• Regeneration of the liver is a classic example of repair by regeneration. It is triggered by cytokines and growth factors produced in response to loss of liver mass and inflammation. In different situations, regeneration may occur by proliferation of surviving hepatocytes or repopulation from progenitor cells.