3. Experimental Methods I: The Anatomically Well-Defined Wound

The experimental space that is most suitable for a study of induced organ regeneration consists of a volume of freshly injured tissue, generated by excising all nonregenerative tissues (typically stroma), which is marked by unambiguous anatomical boundaries, and is physically contained to prevent loss of wound exudate and entry of extraneous tissues or bacteria. These characteristics define the anatomically well-defined wound, referred to also as “defect” in this volume. With skin, the full-thickness excisional skin wound (dermis-free defect) in the rodent or the swine satisfies these criteria. In the peripheral nerve, the fully transected nerve (sciatic, typically) in the rat or mouse, with stumps separated by a critical gap length is a widely used defect that satisfies these criteria. The partial thickness or incisional skin wounds and the hemisectioned nerve trunk do not meet the criteria for an anatomically well-defined defect.