Visualization of biological specimens by cryoHVEM.

This article describes the operation and the characteristics of cryoHVEM imaging of biological specimens using a top-entry cryostage. The procedure for inserting frozen specimens into the microscope column is also presented. Whole mounts were observed under optimal imaging conditions by combining: fixation by fast freezing for structure preservation without exposure to chemicals, observation in the hydrated (frozen) state or in the dried state without exposure to the atmosphere after the initial fixation by freezing, and ultrastructural visualization with the key imaging factors of resolution, penetration and beam-induced damage at their best by high-voltage electron microscopy.