Objective:To probe into the changes of skin extended by presuturing in respect to biomechanic alteration

source of extended skin

scope of skin involved in extension and histological changes to provide an experimental basis for clinical application.Methods:The white piglet was adopted as animal model.The parameters observed were as follows:area of extra skin obtained histolgical changes

stress-stain relation of skin under stretch

anti-tensile.Results:The results showed that at 24hr

45hr and 72hr after presuturing

the areas of skin extended

and the length of skin were increased.The thickness of epidermis and dermis of stretched skin were thinner.The area with maximum extension was located in 1～2 cm away from stretching borders.The electron microscopic observation showed that in the rough endoplasmic reticulum of fibroblasts

vacuolar degeneration could be seen.Stress-strain relation showed that extensile force decreased with the passage of time.Conclusion:①Stress-stain relation shows that extensile force decreases with the passage of time.②The sources of extended skin include:the displacement of adjacent tissue and the extension of stretched skin and the proliferation of tissue.③The area affected by stretching is mainly limited within 5cm adjacent to stretching border.④The anti-tensile strength of healing wound of extended skin is the same as that of normal skin.