Plant-adapted OTO staining improves ultrastructural imaging by transmission electron microscopy

Transmission electron microscopy (TEM) is commonly employed to study plant cellular ultrastructure; however, sample preparation can be problematic due to polysaccharide-rich cell walls, large vacuoles, and intricate membrane systems that hinder staining and structural preservation. Researchers have now devised a plant-specific TEM preparation technique utilizing a modified osmium-thiocarbohydrazide-osmium (OTO) staining process, alongside refined washing, dehydration, and resin infiltration procedures.

By applying this optimized method to tomato roots and leaves, the scientists demonstrate that it results in clearer backgrounds, sharper cellular boundaries, and more accurate representation of cellular morphology as compared to traditional preparation methods. The technique enhances the visibility of fine membrane-associated structures, such as mitochondrial cristae, chloroplast grana and stroma lamellae, nuclear membranes, and other endomembrane structures.

Simultaneously, it minimizes staining-related precipitates and diffuse background artifacts, offering a practical solution for obtaining high-contrast TEM images of plant tissues and enabling detailed ultrastructural analysis of plant cells and organelles.