ABC of Safety in the Biological Sciences
Frozen sections are widely used in biological sciences laboratories for urgent diagnosis, some silver impregnation and neuropathology techniques, enzyme histochemistry, the analysis of lipid distribution and immunohistochemistry.
Tissues are either fresh or fixed and sections are produced in a cryostat or with a freezing microtome (using carbon dioxide or a thermocouple for cooling). Fresh tissues must be treated as potentially infectious and handled appropriately.84 All equipment used to prepare frozen sections from fresh tissue needs to be cleaned and disinfected regularly. In addition, when cutting frozen sections, take care to prevent injury from the microtome knife. Cover any open cuts to prevent inoculation contamination during cutting and avoid the cold temperature of the cryostat as frostbite can occur at -15°C.
When using a freezing microtome with carbon dioxide or a thermocouple device for freezing keep exposed skin away from all cold surfaces. Ear protection ('muffs') may be necessary since the noise levels from expelling carbon dioxide from the gas cylinders are considerable. Carbon dioxide should only be used when there is adequate ventilation. If persons are overcome by excess carbon dioxide, remove to fresh air and if necessary, apply resuscitation.