As long as possible. I remember reading somewhere about TB in lung tissue that was still viable after *years* of 10% NBF. Make sure the lungs are thoroughly perfused, or they will still be unfixed in the middle. There is a technique to "inflate" lungs at autopsy using a large syringe full of NBF and a clamp. Make sure that the specimen is not contacting the walls or bottom of the specimen container. You can suspend the whole organ with string inside the container, if needed. One can also use gauze or paper towels to keep the organ under the surface of the fixative. Lung tissue is notoriously difficult to fix properly, due both to the high lipid content of the pleural parenchyma, and the fact that fresh lungs float.
Sincerely, Jay A. Lundgren, M.S., HTL (ASCP) _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet