Jailenne I. Quiñones-Rodriguez and Thomas Schikorski

Department of Anatomy and Cell Biology, Universidad Central del Caribe, School of Medicine,

Bayamón, Puerto Rico

Chemical fixation is nearly indispensable in the biological sciences, especially in circumstances where cryo-fixation is not applicable. While universally employed for the preservation of cell organization, chemical fixatives often introduce artifacts that can confound identification of true structures. However, toxicity of formaldehyde causes an environmental concern and may demand substitution of this reagent. Glyoxal has become a prominent substitute to formaldehyde as a modern chemical fixative because of the health safety profile, faster reaction rate and selective control over crosslinking. Using light and electron microscopy, we highlight how adequate fixation can lead to an improvement in ultrastructure and increase antigenicity of cellular components in neuron synaptic vesicles. The overall synaptic morphology has traditionally been studied by electron microscopy, which enables the visualization of synaptic structure in detail. Besides, the higher speed of membrane penetration seen with glyoxal was coupled to a better preservation of the general cell morphology, as observed by imaging cells during fixation. The immunostaining intensity of all these structures, defined by the fluorescent protein signals, has a tendency higher after glyoxal fixation. Indeed, using the glyoxal fixation in electron microscopy, showed a submicroscopic organization of the most membranous structures of the cytoplasm similar to PFA, this similarity extends to some of the fine organelle’s structural details but also to cytoskeletal assemblies. We showed that glyoxal can be a valuable and superior alternative to PFA for light and electron microscopy.

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