A Modular and Automated Serial Section Collection System for Ultramicrotomy and Subsequent Imaging

Abstract

Abstract Ultramicrotomy with automated section collection enables a reliable collection of sequential sections for 3D imaging. Here, we introduce a system for collecting several hundred ultra-thin sections on tape as a flexible polymeric substrate. The tape is stored within a portable cassette, which can be used as a modular platform for different applications. The motorized cassette with its retractable section collection cantilever is installed in front of an ultramicrotome for section collection. Section collection and imaging of the sections can be conducted without requiring any manual handling of the tape, which reduces the risk of specimen contamination and offers various options for automatization and cross-compatibility. For instance, processing steps such as a plasma glow-discharge of the substrate can be performed on the tape while it is enclosed in the cassette. As a proof of concept, more than 300 sequential sections at a thickness of 150 nm were cut from a polymer blend sample and collected on a metal-coated tape. Finally, a subset of 15 × 15 × 15 µm³ of the original sample volume was successfully imaged by confocal Raman microscopy and reconstructed at submicron resolution. The serial section cassette harbors the potential to standardize, simplify, and automate sample library collection, imaging, and storage.