I am cutting frozen sections of mouse mammary gland for immunofluorescence.
The mid lactation stages are pretty easy.  The pregnant stages however are
a greasy mess.  The gland accumalates a huge amount of fat during pregnancy
which is lost during lactation.  I am cutting the pregnant glands at the
lowest possible temperature(I put blocks of dry ice in the cryotome).  I
fix the gland in paraformaldehyde prior to freezing.  Does anyone know how
to make my block harder in a way that will not interfear with antigenicity?

Neal