Rethinking tissue preservation: A review of non-toxic and environmentally sustainable fixatives

Abstract

Fixatives are substances used in histopathology to preserve tissue samples by preventing degradation and keeping them structurally intact for microscopic analysis. The common examples include formaldehyde, glutaraldehyde, and alcohols. The widely used fixative, formaldehyde, carries significant health hazards, like respiratory distress, mucosal irritation and carcinogenic effects. Consequently, there is a growing academic impetus to explore natural alternatives to traditional chemical fixatives. Studies were obtained from PubMed database using keywords that covered a wide range of fixatives, including natural, formalin-based, sugar-based, plant-based, and alternative options. Collected data was analyzed and organized into four categories of naturally available fixatives: Aloe vera, Honey, Jaggery, Sugar. 11 studies were included from January 2013 to March 2024. In these, the alternative fixatives has been used for tissue processing. Honey was tested eight times at concentrations of 10 %, 20 %, and 100 %; jaggery six times at 30 % and 100 %; Sugar was used as sugar syrup three times at 20 % and 100 %, as sirka once and as sugarcane vinegar in one study; aloe vera once at 20 %; ethanol twice at 95 %; and formalin nine times at 4 % and 10 %. Compelling evidence demonstrates that natural fixatives can provide tissue preservation on par with formalin, particularly in short-term applications. Although these fixatives are harmless, they come with certain disadvantages Honey has shorter shelf life; Jaggery cause mold formation and produces discoloration of sample; Sugar attracts insects and leads mold formation; Aloe vera produce poor nuclear staining and cell morphology preservation.