Evaluation Summary:
Meechan et al. present a systematic approach to semi-automate an ultramicrotome operation for targeting a specific plane aided by x-ray tomography measurements. It is a fundamental work of great interest to any users of using electron microscopy (EM), particularly when targeting the imaging of thin sections in a select region of interest by ultramicrotomy, or when targeting volume EM of select sample regions. The manuscript documents with exceptional detail a workflow including both microtome modifications and software adaptations for semi-automated targeting of structures with micrometer precision, resulting in a faster and more accurate orientation of the image acquisition planes for volume electron microscopy, a task that has traditionally been difficult and time-consuming. Therefore, this work will reduce sample preparation labor and, critically, facilitate the comparison of the ultrastructure of multiple samples. The method is based on X-ray imaging acquisition prior to any sectioning and proposes a solution for the two instruments commercially available in the field, and by transparently sharing all the data, hardware, and software, and by describing every detail of the workflow, this fundamental method can be readily adopted by any practitioner, enabling its wide application - it is a key step in the field regarding speed-up, accuracy, and reproducibility in electron microscopy.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1, Reviewer #2 and Reviewer #3 agreed to share their names with the authors.)