<prompt> Which of the following is true with regards to wound healing?Collagen I is gradually replaced by collagen III in wound healingWound strength is 70 after 4 weeks of wound healingMyofibroblasts may lead to large skin defects being reduced to 5 to 10 of their original size within 6 weeksMaximum wound strength is achieved after 2 years  <response>: 1. At first a provisional matrix containing fibrin, plasma fibronectin, and type III collagen is formed, but in about 2 weeks this is replaced by a matrix composed primarily of type I collagen. 2. After 4 weeks of wound healing, the strength of the wound is only 10. 70 of the wound strength is only achieved after about 10-12 weeks of wound healing. 3. The initial steps of wound contraction involve the formation, at the edge of the wound, of a network of myofibroblasts, which are modified fibroblasts exhibiting many of the ultrastructural and functional features of contractile smooth muscle cells. Within 6 weeks, large skin defects may be reduced to 5 to 10 of their original size, largely by contraction. 4. Wound strength reaches approximately 70 to 80 of normal by 3 months but usually does not substantially improve beyond that point. 