Expression of fibronectin and tenascin as a demonstration of vital reaction in rat skin and muscle.

The efficiency of immunohistochemical techniques for the diagnosis of vitality of wounds decreases for lesions occurring fairly close to death. We analyzed the expression of fibronectin (FN) and tenascin (TN) in wounds inflicted in abdominal skin of 12 adult rats. An incised injury was made at 5, 10 or 15 min before death and another at 5 min after sacrifice, and collected after 45 min. Formalin-fixed paraffin-embedded sections from a total of 36 samples (mean 1.5 per wound) were immunostained following the streptABC technique. Microscopic examination revealed a reticular pattern staining in 18 out of 20 vital samples for FN, 16 out of 20 for TN, 2 out of 16 postmortem samples for FN and 3 out of 16 for TN. Intracellular staining of muscle fibres was observed in 7 out of 20 vital and 5 out of 16 postmortem samples. FN and TN were detected in most of the vital injuries but they are not completely specific. Postmortem staining occurred in a few cases probably related to a passive extravasation of these molecules from damaged blood vessels. Reactivity of muscle fibres occurs both in vital and postmortem lesions, and is not useful in the diagnosis of vitality.