Effects of histological processing on lectin binding patterns in oral mucosa and skin

The effects of fixation and wax processing on lectin binding to C3H mouse palate and tail skin were evaluated using eight FITC-conjugated lectins. Sections and blocks of tissue were fixed in acetone, ethanol, methanol, formalin, glutaraldehyde or Bouin's picric-acetic-formalin fixative. Tissue blocks were then processed to paraffin wax. Compared to unfixed cryostat sections, there was a weaker but similar pattern of surface binding to sections of fixed and wax-processed tissues with acetone, alcohols and Bouin's fixative. Basement membrane binding was much weaker with acetone-wax and absent when alcohols or Bouin's fixatives were used. Tissues fixed in formalin showed very weak general binding, while glutaraldehyde fixation resulted in considerable non-specific cytoplasmic binding. Acetone, alcohols or Bouin's fixative followed by processing to paraffin wax provided convenient acceptable alternatives to the use of unfixed cryostat sections. Lipid extraction prior to lectin incubation resulted in complete elimination of detectable binding to epithelium suggesting that lectin-binding sites in the cell surface are associated with glycolipid or lipid.