Figure 2
Wound healing in mouse fetuses. (a) Gross photograph at 72 h after wounding showing complete skin regeneration without scarring in E13 wounds. Visible marks were observed in wounds made at E14 or later. All wounds showed subcutaneous DiI uptake, which labeled the wound site. Scale bar = 1 mm. (b) Representative image obtained 72 h after wounding. The skin texture was regenerated, and the wound was almost free of depression compared to the surrounding normal skin in E13 wounds, but a visible mark and depressions in the surrounding skin were observed in E14 wounds. In addition, inside the visible mark in E14 wounds, the roughness was reduced compared to that of normal skin. (c) Comparison of the wound 72 h after wounding. n = 5 for each developmental stage. (d) H&E staining of the wound after 72 h showing healing of the dermis and other structures up to E16, but the dermis was replaced by thick scar tissue at E17. Scale bar = 100 µm. (e) Timing of the transition between epidermal and dermal regeneration during mouse development. (g) Regeneration of the epidermis and dermis over time, focusing on the wound margin. H&E images. In E13 wounds, the dermis moved into the skin defect earlier than the epidermis. In wounds made at E14 or later, the epidermis moved into the wound earlier than the dermis, and the leading edge contacted the fascia. In E16 wounds, the dermis regenerated, but in E17 wounds, cells derived from the fascia accumulated in the wound, forming scar tissue. Scale bar = 100 µm. (g) SEM images of wound healing at E13, E14, and E15. Scale bar = 200 µm.
