In addition, the plasminogen tissue activator has value of 3 times higher in the parietal membrane than in the dura mater, while the visceral membrane of the haematoma does not contain this factor, which exudates from the extremely vascularized parietal membrane, transforms plasminogen in plasmine in the subdural haematoma, by neutralizing the fibrinogen and fibrin and favoring continuous micro bleedings. This evidence concerns the gene PLG and Subdural hemorrhage.