*Prepare the following protocol in a fume hood.*

To Prepare 1 liter of Fixative

1. 900ml dd H₂O + 500µl 1N NaOH
2. Heat to 65° - 70°C
3. While stirring, add 20g paraformaldehyde
4. Continue heating and stirring until paraformaldehyde is dissolved
5. Let cool to room temperature
6. Add 100ml of 10X PBS
7. pH to 7.3 with HCl
8. Sterile filter
9. Store at 4°C, protected from light

This reagent is good for at least one month.