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Treat embryos with bleach (0.5% solution for 2 min) before removing the chorions. Decant the bleach solution and rinse with 10% sterile Hank's saline. Remove the chorions with watchmaker's forceps or by soaking the embryos in Pronase (see Removing Embryos from Chorions, page 4.3). Embryos that can move should be anesthetized by soaking in tricaine or by chilling on ice. Embryos can be dissociated with 0 Ca{^}2+^up to about 16 hpf of development. Older animals should be dissociated with the protease treatment or by dissection.