Primary intentional healing which is true ?
Ans. is 'a' i.e., Neovascularization is maximum by day 5Skin wound healingSkin wounds are classically described to heal by primary or secondary intention.A. Healing by primary intention It occurs in wounds with opposed edges, e.g., surgical incision.The healing process follows a series of sequantial steps : ?Immediate after incision Incisional space filled with blood containing .fibrin and blood cells.Dehydration of the surface clot forms scab that covers the wound.Within 24 hours Neutrophils appear at the margins of wound.In 24-48 hoursEpithelial cells move from the wound edges along the cut margin of dermis, depositing basement membrane components as they move.They fuse in the midline beneath the surface scab, producing a continuous but thin epithelium layer that closes the wound.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.By day 5Incisional space is largely filled with granulation tissue.Neovascularization is maximum.Collegen fibrils become more abundant and begin to bridge the incision.The epidermis recovers its normal thickness.During second weekLeukocytes and edema have disappeared.There is continued accumulation of collegen and proliferation of fibroblast.By the end offirst month Scar is made up of a cellular connective tissue devoid of inflammatory infiltrate covered now by intact epidermis.B. Healing by secondary intention It occurs in wounds with seperated edges in which there is more extensive loss of cells and tissue.Regeneration of parenchymal cells cannot completely restore the original architecture, and hence abundant granulation tissue grows.Healingby secondary from primary intention in several respects : Inflammatory reaction is more intense.Much larger amounts of granulation tissue are formed.Wound contraction occurs - Feature that most clearly differentiate secondary from primary healing.Permanent wound contraction requires the action of myolifibroblasts - Fibroblasts that have the ultrastructural characteristic of smooth muscle cells.
Neovascularization is maximum by day 5
Neovascularization is maximum by day 3
Neutrophils appear at wound margins on day 3
The epidermis recovers its maximum thickness by day 7