Abstract: Objective To investigate the time-dependent recruitment and differentiation of fibrocytes in skin wound healing. Methods Fibrocytes （expressing CD45 and procollagen Ⅰ） and myofibroblasts （expressing CD45 and α-SMA） were co-localized by immunofluorescent staining. The number of fibrocytes and myofibroblasts was counted at different post-wounding interval. Results At 3 d after injury, fibrocytes started to recruit at the margin of the wounds. At 5 d after injury, myofibroblasts started to appear in new formed granulation tissue. The number of fibrocytes and myofibroblasts peaked at 7 d post-wounding. Conclusion During skin wound healing, myofibroblasts in granulation tissue originated at least partly from fibrocytic differentiation. The time-dependent recruitment and differentiation of fibrocytes may provide new information for wound age determination.

Key words: forensic pathology, wounds and injuries, skin, fibrocyte, myofibroblast, wound age, mice