Morphology of the hemostatic plug in human skin wounds: transformation of the plug.

The transformation of hemostatic plugs in human skin wounds was studied in vivo after bleeding had stopped. Standardized bleeding time incisions were made on the dorsal side of the forearm of four normal male volunteers. The wounds were excised by punch biopsy 10 minutes, 30 minutes, or 2 hours after they had been made and studied by light and electron microscopy. The wounds were filled with red blood cells, and a network of fibrin strands was found in the wound, particularly near transected vessels. Polymorphonuclear leukocytes were encountered within transected vessels and at 2 hours also in the wounds and in concentric rings around the vessels up to 0.5 mm. from the wound. On top of the wounds a superficial scab, consisting of red blood cells and presumably air-dried proteins, had formed. Hemostatic plugs were found at the ends of transected blood vessels. At 10 minutes the plugs consisted of largely degranulated platelets which showed strong interdigitation. Fibrin was still absent from the center of the plugs. At 30 minutes the platelets became less densely packed, and small fibrin fibers were deposited between the platelets in large peripheral areas of the plugs. At 2 hours some of the platelets had assumed rounded shapes with few interdigitations and larger spaces between them. Areas in the plug with platelets that had lost their integrity alternated with areas where platelets still had their cytoplasmic matrix and were interdigitated. Fibrin fibers were especially demonstrable between the degenerated platelet vesicles. This occurred everywhere in small hemostatic plugs and in the periphery of larger plugs. In one individual it was also observed in the center of large hemostatic plugs. In the other individuals fibrin was present centrally as amorphous dark staining material which was fibrillar in tangential sections.