The subcutaneous capsules for foreign body in fetal rabbits: preliminary report.

In terms of wound healing, there are fundamental intrinsic and extrinsic differences between fetuses (scar-free healing) and adults. The fetus exhibits less typical inflammatory response (significantly neutropenic) with an underdeveloped self-nonself immunologic identity and a lack of cellular immunity. The recruitment of inflammatory cells to a wound may play an important role in the resulting cellular processes and ultimately affect the quality of the healing response. Foreign bodies can act as a source of infection and immunologic reactions. In contrast, there have been few studies of the wound healing of fetus with foreign bodies, where in adults, wounds are healed by tissue regeneration rather than capsule formation and a foreign body reaction. In this study, the wound healing process in an adult rabbit and fetus group, in which either silicone or a sponge was inserted in the uterus, were compared. All specimens showed capsule formation with fibroblast, collagen deposition, neovascularization, and infiltration of inflammatory cells. However, the fetal specimen exhibited mainly acute inflammatory responses and the capsule contained less fibroblasts and collagen deposition. In addition, myofibroblast expression, which mediates wound contracture, was lower in the fetal specimen. These findings were common with cotton implants, which were expected to induce a severe inflammatory response. The inflammatory response induced by foreign materials in fetal tissue showed similar response with that of incisional wound healing. This study may provide a basis for the use of implants such as silicone in future fetal surgery.