A modified ferric tannate method for visualizing a blood vessel and its usage in the study of spinal cord injury

Study design: To develop a method for the study of spinal cord injury (SCI) that can visualize the blood vessels and is compatible with hematoxylin and eosin (HE) staining and immunohistochemical techniques. Objective: Visualization of the vascular changes is important for the study of SCI. The original ferric tannate method can stain the spinal cord vasculature to its terminals, but the diffuse tannate precipitates spoil the delicacy of the picture. More importantly, it is incompatible with HE staining and immunohistochemical techniques, which is crucial for the study of SCI. We thus aimed to develop a modified ferric tannate method that could meet the requirement for the study of SCI. Setting: This study was carried out in China. Methods: The original ferric tannate method involves a two-step procedure: intravascular perfusion of tannic acid, followed by soaking the tissue sections in a solution of ferric chloride. In the modified method both chemicals were delivered through perfusion. Results: In the original method, diffuse ferric tannate precipitates blurred the profile of the vessels. More importantly, it was incompatible with either HE or immunostaining methods. Our modified method stained the blood vessels with clean background and was compatible with both HE staining and immunohistochemical techniques. Conclusion: The modified method is far superior to the original method and meets the requirement for the study of SCI. Spinal Cord (2009) 47, 852-856; doi:10.1038/sc.2009.30; published online 7 April 2009