Picric Acid, saturated aqueous - 75ml
Formalin (37-40% formaldehyde) - 25ml
Glacial Acetic Acid - 5ml
Combine all three to make up fixative.
Hopwood, D. (1990). Fixation and fixatives. In Bancroft, JD. et al. (eds). Theory and practice of histological techniques. Churchill Livingstone, New York, p21-42
After fixing the tissue if the tissue is big in size it can be fixed 24hrs first and then taken out cut into pieces and again fix in the same solution for another 24hrs. After fixation the sample should be washed and can be kept in 70% alcohol (30% then 50% and finaly 70%) till it used for further work to avoid hardening of tissue (if kept in fixative itself tissue will become hard)