ABSTRACT
Prior to use of any immunocytochemical method, sections must be pretreated to present a hydrophilic surface, and when applicable, antigenic epitopes must be demasked and precautions taken to avoid unspecific and unwanted reactions with antibodies. Although virtually all immunocytochemists agree that use of inert protein blocking of unspecific binding sites is necessary in nearly all immunocytochemical methods, many different approaches have been taken. It is certain that pretreatment of sections with inert proteins considerably reduces unspecific, unwanted staining. If the combination of adequate fixation, tissue pretreatment, and primary antiserum is acceptable, positive staining will be evident. With the lowest dilutions of antisera, overt unspecific tissue staining may be apparent. Thus, mildly fixed tissue specimens may be subject to some morphological damage and, possibly, extraction of antigens during the long incubations. An alternative to tissue powder absorption is to use serum from the species to be studied coupled to a solid support as an immunosorbent.
