Paraformaldehyde for mouse brain (4% PFA)
Paraformaldehyde powder (e.g., EMD)
Phosphate buffer for mouse brain (0.2 M)
To make 200 mL of PFA, add 100 mL of H2O to a 500-mL glass bottle (e.g., Pyrex) containing a stir bar. Heat to 60°C on a magnetic heating plate (keep this temperature during the whole preparation). Add 8 g of PFA powder, then gradually add 100 mL of 0.2 M phosphate buffer and stir until most of the PFA is dissolved. Let cool to below 40°C and filter (e.g., using a Nalgene filter unit). Store at 4°C. PFA should not be prepared more than 3 d before use.
Prepare solution in a chemical fume hood.
