Time from tissue acquisition to fixation should be as short as possible.
Long term storage in alcohol may harm some rare antigens and phosphoproteins; specificity and quality of an antibody recognizing such “difficult” protein should be properly tested prior to use.
High static electricity may cause sticking of the sections on the blade holder. To avoid this, wet the paraffin block with water. It will help for two next slices and then the blocks must be wetted again.
In situ hybridization could be also performed on paraffin embedded tissue samples. For this purpose, fixation overnight in buffered 4% formaldehyde is recommended.
Liver is quite sensitive to overfixation. To avoid tissue spalling during sectioning do not fixate liver in 4% formaldehyde longer than 24h.