What is Primary intentional healing which is true - and explain in detail?
Ans. is 'a' i.e.. Neovascularization is maximum by day 5 Skin wound healingo Skin wounds are classically described to heal by primary or secondary intention.Healing by primary intentionIt occurs in wounds with opposed edges, e.g., surgical incision.The healing process follows a series of sequential steps : -o Immediate after incisionIncisional space filled with blood containing fibrin and blood cells.Dehydration of the surface clot forms a scab that covers the wound,o Within 24 hoursNeutrophils appear at the margins of the wound.o In; 24-48 hoursy Epithelial cells move from the wound edges along the cut margin of the dermis, depositing basement membrane components as they move.y They' fuse in the midline beneath the surface scab, producing a continuous but thin epithelium layer that closes the wound,o By day 3Neutrophils are largely replaced by macrophages.Granulation tissue progressively invades the incision space.Collegen fibers now present in the margin but do not bridge the incision,o By day 5Incisional space is largely filled with granulation tissue.Neovascularization is maximum.Collagen fibrils become more abundant and begin to bridge the incision.The epidermis recovers its normal thickness,o During the second weekLeukocytes and edema have disappeared.There is continued accumulation of collagen and proliferation of fibroblast,o By the end of the first monthThe scar is made up of a cellular connective tissue devoid of inflammatory infiltrate covered now by the intact epidermis.Healing by secondary intentionIt occurs in wounds with separated edges in which there is a more extensive loss of cells and tissue.Regeneration of parenchymal cells cannot completely restore the original architecture, and hence abundant granulation tissue grows.Healing by secondary intention differ from primary intention in several respects : -The inflammatory /7 reaction is more intense.Much larger amounts of granulation tissue are formed.Wound contraction occurs - Feature that most clearly differentiate secondary from primary healing.o Permanent wound contraction requires the action of myofibroblasts - Fibroblasts that have the ultrastructural characteristic of smooth muscle cells.