A simple device for obtaining complementary fracture planes at liquid helium temperature in the freeze‐etching technique

SUMMARY This paper describes a simple technique for obtaining complementary replicas of specimens fractured under liquid helium. Ordinary hollow brass rivets are used as specimen holders and are frozen in an end‐to‐end position. The pairs of rivets are placed in a device consisting basically of two concentric steel tubes which can be twisted and moved relative to each other guided by a peg‐in‐slot mechanism. The rivets are inserted while the device is under liquid nitrogen, and the device is then transferred to liquid helium and the tubes are moved so that the upper rivet is knocked away and falls into a collector. The device is then transferred back to liquid nitrogen, the fracture faces being protected from contamination throughout the process. Replicas are then obtained by any of the standard methods for specimens fractured under liquid nitrogen. The device has been tested using yeast cells as a model system, and some typical results are presented and discussed.