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    • CommentAuthorjuruble
    • CommentTimeJun 22nd 2007 edited

    This protocol explains how to: cysteine eggs to remove the jelly coat and separate them into dishes.

    Protocol revised: 3/19/2007

    Protocol written by: Julie Ruble

    1. Mix up enough cysteine in a small beaker for the number of dishes of eggs you obtained from squeezing.
    2. If you squeeze eggs in the morning, you should cysteine that afternoon. You don't have to wait too long after fertilizing to cysteine, but it helps to wait a couple of hours so you can tell which eggs are good.
    3. Pour the 20% Steinberg's off of one dish of eggs and pour enough cysteine over them to cover eggs. Wait 1-2 minutes until jelly coat is dissolved (can swirl slightly to help you judge). Note: Have ethanol in waste container to euthanize any eggs you put there.
    4. Prepare several petri dishes with 20% Steinberg's to receive good eggs.
    5. Under low magnification on the double-headed microscopes, use a fire-polished pipette with a rubber bulb (or a plastic pipette cut off to make it smooth) to suck up good eggs* and gently expel them into your fresh dishes of Steinberg's (under surface of the Steinberg's so that they don't touch air, or they can explode). Put about 30-40 eggs in each dish.
    6. Dispose of any excess eggs in waste container and then wash out waste container and sink when you're finished.
    7. Put dishes in refrigerator or room temperature depending on the speed of development you desire.

    *Use the following guidelines to determine if eggs are good or bad:

    GOOD EGGS (right in the picture, below):
    -dark side up
    -cells dividing
    -no discoloration

    BAD EGGS (left in the picture, below):
    -smooth (e.g. no evidence of division)
    -oozy or mushy
    -white side up

    good and bad eggs


    Be very careful to avoid engorged, "bad" eggs when undertaking the cysteining process. I cannot say for sure, but it seems that the bursting of these "mines" may lead to more conversion from good to bad eggs.

    • CommentAuthorvbeamer
    • CommentTimeMay 14th 2012
    I would suggest having a rinsing dish of 20% Steinberg's solution before placing them in the final petri dish that will go in the fridge. Any transferred cysteine solution will be diluted so it will not affect the embryo development.