Cryo-Planing Biological Specimens for Scanning Electron Microscopy

Abstract

Cryo-planing SEM provides a powerful 3D view of internal and external tissue and cell features. However, specimen preparation is tedious because it requires custom apparatus and difficult cryogenic manipulations. We present an easy method using mPrep/s capsules that provide a “handle” to hold and orient specimens throughout cryo-preparation and imaging. Cryo-facing is done with a cryo-ultramicrotome, requiring no custom equipment while providing accurate control of the image plane. We show this with fresh Christmas cactus leaves and aldehyde-fixed kidney tissue imaged by room temperature SEM after freeze-drying, demonstrating the method operating without an expensive cryo-SEM.