In situ X-ray assisted electron microscopy staining for large biological samples

Sebastian Ströh, Eric W. Hammerschmith, David W. Tank, H. Sebastian Seung, Adrian A. Wanner

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Electron microscopy of biological tissue has recently seen an unprecedented increase in imaging throughput moving the ultrastructural analysis of large tissue blocks such as whole brains into the realm of the feasible. However, homogeneous, high quality electron microscopy staining of large biological samples is still a major challenge. To date, assessing the staining quality in electron microscopy requires running a sample through the entire staining protocol end-to-end, which can take weeks or even months for large samples, rendering protocol optimization for such samples to be inefficient. Here we present an in situ time-lapsed X-ray assisted staining procedure that opens the “black box” of electron microscopy staining and allows observation of individual staining steps in real time. Using this novel method we measured the accumulation of heavy metals in large tissue samples immersed in different staining solutions. We show that the measured accumulation of osmium in fixed tissue obeys empirically a quadratic dependence between the incubation time and sample size. We found that potassium ferrocyanide, a classic reducing agent for osmium tetroxide, clears the tissue after osmium staining and that the tissue expands in osmium tetroxide solution, but shrinks in potassium ferrocyanide reduced osmium solution. X-ray assisted staining gave access to the in situ staining kinetics and allowed us to develop a diffusion-reaction-advection model that accurately simulates the measured accumulation of osmium in tissue. These are first steps towards in silico staining experiments and simulation-guided optimization of staining protocols for large samples. Hence, X-ray assisted staining will be a useful tool for the development of reliable staining procedures for large samples such as entire brains of mice, monkeys or humans.

Original languageEnglish (US)
Article numbere72147
StatePublished - 2022

All Science Journal Classification (ASJC) codes

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • General Neuroscience


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