Preservation of cellular structure via immersion fixation in brain banking

Authors

  • Macy Garrood Apex Neuroscience, Salem, Oregon, USA
  • Emma L. Thorn Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, New York, USA
  • Adam Goldstein Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, New York, USA
  • Allison Sowa Microscopy and Advanced Bioimaging Core, Icahn School of Medicine at Mount Sinai, New York, New York, USA
  • William Janssen Microscopy and Advanced Bioimaging Core, Icahn School of Medicine at Mount Sinai, New York, New York, USA
  • Alyssa Wilson Departments of Neurology and Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, USA
  • Claudia S. López Multiscale Microscopy Core, Oregon Health and Science University, Portland, Oregon, USA; 7 Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon, USA
  • Raakhee Shankar Multiscale Microscopy Core, Oregon Health and Science University, Portland, Oregon, USA
  • Erin S. Stempinski Multiscale Microscopy Core, Oregon Health and Science University, Portland, Oregon, USA
  • Kurt Farrell Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, New York, USA
  • John F. Crary Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, New York, USA
  • Andrew T. McKenzie Apex Neuroscience, Salem, Oregon, USA

DOI:

https://doi.org/10.17879/freeneuropathology-2025-6104

Keywords:

Brain banking, Immersion fixation, Histology quality, Postmortem interval, Myelin, Synapse, Vacuolization, Volume electron microscopy

Abstract

Immersing the brain in a solution containing formaldehyde is a commonly used method for preserving the structure of human brain tissue in brain banking. However, there are questions about the quality of preservation using this method, as formaldehyde takes a relatively long period of time to penetrate a large organ such as the human brain. As a result, there is a critical need to determine whether immersion fixation is an adequate initial preservation method. To address this, we present exploratory histologic findings from our brain bank following the immersion fixation of hemi-sectioned brain specimens under refrigeration. Using light microscopy, we found that there was no significant change in the size of pericellular or perivascular rarefaction areas based on the postmortem interval (PMI) or on the progression from the outer (frontal cortex) to the inner (striatum) brain regions. Additionally, we did not identify any significant number of ghost cells – a state of late-stage cellular necrosis – in the light micrographs analyzed. Using transmission electron microscopy of tissue from the frontal cortex, we found that synapses could still be visualized, but there was vacuolization and variable degrees of myelin disbanding identified. Using serial section transmission electron microscopy, we found that identified synapses could be traced from one section to the next. Using serial block face scanning electron microscopy, we also found that myelinated axons on 2D images can be traced with high fidelity from one image to the next, even at PMIs of up to 27 hours. Collectively, our data corroborate previous findings that immersion fixation is effective for prevention of cellular necrosis and for visualizing many ultrastructural features in at least the surface areas of the brain. However, how structural preservation quality should best be assessed in brain banking is an open question that depends on the intended research applications.

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Published

2025-02-04

How to Cite

Garrood, M., Thorn, E. L., Goldstein, A., Sowa, A., Janssen, W., Wilson, A., López, C. S., Shankar, R., Stempinski, E. S., Farrell, K., Crary, J. F., & McKenzie, A. T. (2025). Preservation of cellular structure via immersion fixation in brain banking. Free Neuropathology, 6, 4. https://doi.org/10.17879/freeneuropathology-2025-6104

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Original Papers