Abstract
High resolution episcopic microscopy (HREM) produces digital volume data by physically sectioning histologically processed specimens, while capturing images of the subsequently exposed block faces. Our study aims to systematically define the spectrum of typical artefacts inherent to HREM data and to research their effect on the interpretation of the phenotype of wildtype and mutant mouse embryos. A total of 607 (198 wildtypes, 409 mutants) HREM data sets of mouse embryos harvested at embryonic day (E) 14.5 were systematically and comprehensively examined. The specimens had been processed according to essentially identical protocols. Each data set comprised 2000 to 4000 single digital images. Voxel dimensions were 3 × 3 × 3 µm3. Using 3D volume models and virtual resections, we identified a number of characteristic artefacts and grouped them according to their most likely causality. Furthermore, we highlight those that affect the interpretation of embryo data and provide examples for artefacts mimicking tissue defects and structural pathologies. Our results aid in optimizing specimen preparation and data generation, are vital for the correct interpretation of HREM data and allow distinguishing tissue defects and pathologies from harmless artificial alterations. In particular, they enable correct diagnosis of pathologies in mouse embryos serving as models for deciphering the mechanisms of developmental disorders.
Highlights
High resolution episcopic microscopy (HREM) is a technique for generating digital volume data of organic material with volumes of up to 8 × 10 × 15 mm3 in typical numeric isotropic resolutions of 1–5 μm [1]
We systematically reviewed 607 HREM data sets from embryos harvested at embryonic day (E) 14.5
Artefacts were observed in all HREM data examined
Summary
High resolution episcopic microscopy (HREM) is a technique for generating digital volume data of organic material with volumes of up to 8 × 10 × 15 mm in typical numeric isotropic resolutions of 1–5 μm [1]. Its chief domains are the visualization of skin [6,7,8] and the phenotyping of embryos of biomedical models, with a focus on the mouse [9] In the latter, the high quality of HREM data permits detailed visualization of tissue architecture, gross morphology and organ topology in the context of all organ systems of early to late embryos [1,10]. Preparing tissues for HREM imaging requires their fixation, dehydration and embedding in eosin dyed methacrylate resin (JB4, Polysciences). This is similar to preparing specimens for traditional histology and introduces similar artificial changes, Biomedicines 2021, 9, 1711.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call