Healing of 25 mm oblong skin wounds (A) and histology of 6 mm circular skin wounds (B) in wild-type (+/+) and SPARC-null (-/-) mice. In (A) upper panel: an example of the progress of repair processes at the indicated times (days) is shown. S: scab; W: open wound field. In (A) lower panel: percent of wild-type and SPARC-null mice (6 in each group) with healed wounds, defined as loss of the wound scabs and complete covering of the wounds with epidermis, is plotted versus days after the excision. Panel (B) illustrates histologic appearance of 6-mm wounds in a wild-type (+/+) mouse and an SPARC-null (-/-) mouse 4 days after surgery. Granulation (G) tissue formation is more extensive in the wild-type mouse than in the SPARC-null mouse. Arrows indicate reepithelialized wound edge. Reepithelialization appears to be as efficient in mutant mice as in control mice. S: scab; P: panniculus carnosus. Hematoxylin and eosin staining. Scale bar, 210 μm.