Answer
When tissue is damaged, repairs my be effected by parenchyma alone, stromal tissue alone, or if the wound is large, by the combined action of parenchymal cells and stromal cells.
If the wound is small, repair may be adequately effected by parenchyma alone. Parenchymal repair is satisfactory because it preserves the normal functions of the damaged tissue. Bu, in some cases, stromal tissue alone tries to repair tissue damage . This usually results in fibrosis, and scarring and loss of function by damaged tissue. Satisfactory regeneration and preservation of original functions of the tissue require the repair response of both parenchyma and stroma.
Work Step by Step
When a wound is large, both parenchyma, and stroma may work together to effect repair. The stroma provides new collagen fibers, and ground substance to supply structure and strength to the regenerating tissue. Parenchyma cells divide to replace the functional tissue , and blood vessels invade from stroma to supply nutrients and remove wastes. In this cooperative process, the newly regenerating tissue, the granulation tissue, spreads across the wound surface as a protective layer. Granulation tissue comprises capillary buds, collagen fibers, fibroblasts, and inflammatory cells.It facilitates the movement of epithelial cells, and secretes an antimicrobial substance that protects the regenerating tissues from infection. Its formation is important for the proper healing of large wounds.
