Jill:
Pharmingen's CD31 can work on zinc fixative fixed tissue without any antigen
retrievel, which give you very beautiful staining. The optimal concentration is
5ug/ml. The longest time for zinc fixation is 3 days. Following is the recipe
for zinc fixative:
1. Preparation of 0.1M Tris buffer, PH7.4 (1L):
     Tris base      12.1g
     Deionized water     900ml
     1.0N HCL       81.5ml
2. Preparation of Zinc Fixative as follows:
     0.1M      Tris buffer, PH7.4 recipe above (1000ml)
     0.5g Calcium Acetate
     5.0g Zinc Acetate
     5.0g Zinc Chloride
Mix to dissolve, The final PH will be approximately 6.5-7.0. Do not readjust the
PH, as this will cause the zinc to prcipitate out of solution. Store zinc
fixative at Room temperature.

Good Luck

Xudong Wang, M.D
Pharmingen/BD
Department of IHC
(858)812-8800, EXT. 3328