Largescale semithin sectioning method supported by a stainless steel ring enables multiscale analysis in transmission electron microscopy

In transmission electron microscopy, semi-thin sections are prepared and stained with 2% toluidine blue to assess sample integrity and accurately identify regions of interest under light microscopy prior to ultrathin sectioning. This procedure can be challenging for large specimens, especially in attaching semi-thin sections to glass slides without wrinkles. Consequently, semi-thin sections are limited to lengths between 0.2 and 2.0 mm along their longest side, which reduces the amount of structural detail that can be observed. To address this limitation, we have implemented a specialized stainless-steel ring, originally designed for saltwater lures, which eliminates the requirement for costly equipment and specialized technical expertise. The stainless-steel ring protocol enables the production of large, flat, and wrinkle-free specimens (up to 8 mm along their longest side) that adhere securely to the glass slide. This method enables visualization of entire rat female genital organs and mouse small intestine in a single semi-thin section, clearly showing organ connections and lesion sites. Technicians and students can easily create large-scale semi-thin sections without expensive equipment or specialized skills. This approach may expand the use of correlative light and electron microscopy, leading to new discoveries and insights.