Some observations of zebrafish development can be made directly through the chorion.i.
Older embryos require longer in the pronase.
Be sure to rinse the pronase treated embryos thoroughly at least 3 or 4 times to remove all the enzyme. Embryos usually fall out of their chorions with gentle swishing during the rinse. Embryos removed from their chorions can be transferred from one container to another by gently sucking them up with a fire-polished Pasteur pipette or by gentle pouring. The embryos can be brought to the center of the dish for viewing by gently swirling the medium with a circular motion.