Impaling Cells

Impaling the cells with electrodes is a technically difficult thing to do. Oocytes with the follicle cells intact have a very tough outside covering. Also, it is not a rigid cell so the membrane will bend in pretty far before it will rupture and let the electrode in. Finally, the oocyte isn't secured to the bottom of the petri dish so it will slide around. As a result, impaling the oocyte is kind of like trying to poke 2 chop sticks through an under-inflated beachball on ice.

However, with practice it can be done.

To impale the oocyte follow these steps:

1. Start the recording in the Chart program and add a comment saying that you're impaling a new oocyte. Then, slowly bring both electrodes into contact with the cell. Make sure they they are exactly opposite each other. This insures that force put on one electrode will be opposed by the other electrode and won't cause the oocyte to turn or twist. It doesn't matter where the electrodes penetrate the oocyte (animal pole or vegital pole).

2. Advance both electrodes slightly until they indent the cell. This helps to hold the cell in place.

3. Advance the voltage electrode until it pokes into the cell. The cell will become very deformed before it slips in. Don't be discouraged. The hardest part is keeping the force balanced between the two electrodes (so that the oocyte doesn't twist) as you increase the force on the voltage electrode.

4. Once the voltage electrode is in, advance the current electrode until it pierces the cell. Again, the hardest part is trying to stop the oocyte from twisting.

5. After both electrodes are in, wait about 10 minutes for the holes to seal and start an experiment.

The whole impaling process should take 5-10 minute when you get good at it. This is an accelerated version of what it will look like:

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