In regards to the issue of fatty tissues.  I know clinical people want
results as soon as possible and probably throw everything into the
formalin.

BUT in research, we do a lot of fatty mammary tissues and were having this
same problem until the researcher started using Lillies's fixative for all
fatty tissues, and now we get beautiful, fixed tissues throughout the
entire block.  We normally leave them in this fixative for  about 24 hours
minimum before processing on the tissue processor.

I hope this could help you.
Karen Dulany
Eppley Institute for Cancer Research
Omaha, Nebraska
402-559-5123