O PAPEL DE DIFERENTES FIXADORES NA IDENTIFICAÇÃO DA COMPOSIÇÃO DA SECREÇÃO DE COLÉTERES

Abstract

Fixation is a fundamental step in plant anatomy, with its main function being to halt cellular metabolism and preserve the structural integrity and chemical composition of tissues as close as possible to their in vivo state. The choice of fixative agent is a determining factor in sample preparation, as different solutions interact differently with biomolecules, potentially affecting the retention of specific metabolites and the formation of artifacts. In this context, this project analyzes whether different histological fixatives interfere with the results of histochemical tests in the colleters of Genipa americana (Rubiaceae). The study compares the efficacy of two fixatives — FAA50 and Buffered Neutral Formalin (BNF) — in preserving the structural and histochemical composition of colleter secretions. The plant samples were collected, fixed, dehydrated, embedded in resin, and subjected to histochemical tests for the identification of polysaccharides, proteins, and phenolic compounds. The slides were mounted, analyzed, and photographed. The colleters of G. americana occur on the inner surface of the stipules and are of the standard type. Neutral polysaccharides, pectins, acidic mucopolysaccharides, and proteins were observed in the secretion. We found that the choice of fixative affects the preservation of cellular structures and the staining of histochemical test results. The results also demonstrated that FNT performed better in cell preservation, while the FAA stood out for enhancing staining. Thus, this work enriches the field of plant anatomy by showing that the type of fixative should be a strategic choice aligned with the study's requirements.