A flat embedding method to orient thin biological samples for sectioning

Abstract

Microscopy is an important tool used for biological research and has played a crucial role toward understanding of cellular mechanisms and protein function. However, specific steps in processing of biological samples for microscopy warrant improvements to consistently generate data that can more reliably help in explaining mechanisms underlying complex biological phenomenon. Due to their small and fragile nature, some biological specimens such as Arabidopsis thaliana roots are vulnerable to damage during long sample preparation steps. Moreover, when specimens with a small diameter (typically less than 100 μm) are embedded in conventional silicone mold or capsule embedding, it is not only difficult to locate their orientation inside the capsule but also a challenge to obtain good median longitudinal sections. Specimen orientation in particular is crucial because understanding certain plant biological processes such as gravitropism rely on precisely knowing spatial information of cells and tissues of the plant organ being studied. Here we present a simple embedding technique to properly orient small plant organs so that the desired sectioning plane is achieved. This method is also inexpensive and can be accomplished with only minimal equipment and supplies.