Muscle Cross Sectioning - Troubleshooting (May/02/2011 )

My muscle samples have a bunch of holes with in the fibers. Is this freeze artifact or something else? Cutting temp = 25C, frozen in isopentane followed by liquid nitrogen.

Could it be from holding the sample in the isopentane for too long or too little? Could the isopentane be too cold or not cold enough?

Need help!

You've asked this before, haven't you?
Cryoprotection.