1. Chill 200 3d embryos after removing from chorions.
2. Rinse in 0.5% chilled bleach for 2 minutes and then in zero calcium Ringer for 2 minutes.
3. Transfer to a Dounce homogenizer with a mini-mum of liquid and homogenize well.
4. Resuspend in 1 ml L-15 supplemented with 0.3 mg/ml glutamine, 50 U/ml penicillin, 0.05 mg/ml streptomycin and 0.8 mM CaCl2.
5. Store at -20°C.