The effects of various fixatives on subsequent lectin binding to tissue sections

The effects of ten fixation protocols on the subsequent binding of eight lectins to various mouse tissue sites have been systematically evaluated. The fixatives used were neutral and buffered formalin-saline, Bouin's fluid, 95% ethanol, Carnoy's fluid, calcium acetate-paraformaldehyde, and mercuric chloride both before and after removal of mercury pigment. These were compared with frozen sections of unfixed tissue and frozen sections post fixed in paraformaldehyde. Lectins used were PNA, DBA, SBA, BPA, UEA 1, GS I, GS II and MPA. Ethanol was found to be the superior fixative, closely followed by mercuric chloride. Paraformaldehyde was a poor fixative of both paraffin and frozen sections. It is recommended that, where a choice is possible, the fixation protocol appropriate to the particular lectin and tissue binding site is selected. Within certain limitations, formalin-saline proved an adequate fixative for the study of routine paraffin-processed tissue sections.