Frozen Sections & Cryostat Techniques Flashcards

What is the standard method for transferring a frozen section from the cryostat stage to a glass slide?

Answer: Placing a room-temperature slide directly onto the section so it thaws and adheres

The standard method is to place a room-temperature or slightly warmed slide onto the frozen section; the temperature differential causes the section to thaw and adhere firmly to the glass.

What does the abbreviation 'OCT' stand for in the context of cryostat embedding media?

Answer: Optimal Cutting Temperature

OCT stands for Optimal Cutting Temperature, and the compound of the same name is a water-soluble glycol and polyvinyl alcohol mixture that supports frozen tissue at its optimal sectioning temperature.

For intraoperative consultation, what is the accepted turnaround time from specimen receipt to frozen section diagnosis?

Answer: 15–20 minutes

The accepted standard for intraoperative frozen section turnaround is 15–20 minutes from specimen receipt to pathologist diagnosis, which is clinically practical without significantly extending operative time.

Which fixative would cause LOSS of lipids from tissue intended for frozen section lipid staining and should therefore be avoided?

Answer: Absolute ethanol

Absolute ethanol is a lipid solvent and will extract lipids from tissue, making it completely unsuitable for preserving tissue intended for lipid demonstration in frozen sections.

What is a common cause of thick, uneven, or 'chattering' frozen sections in the cryostat?

Answer: A dull or nicked cryostat knife

A dull or nicked knife is a primary cause of chatter (thick, uneven, ridged sections) in cryostat sectioning because the blade cannot cleanly slice through the frozen tissue block.

What is the recommended rapid freezing method to minimize ice crystal artifact when preparing fresh tissue for enzyme histochemistry frozen sections?

Answer: Rapid quenching in isopentane cooled by liquid nitrogen, or CO2 cryospray

Rapid quenching in isopentane cooled by liquid nitrogen (or CO2 cryospray) achieves very fast freezing rates that minimize ice crystal formation while avoiding the violent boiling artifact caused by direct liquid nitrogen immersion.

What is the purpose of 'quenching' tissue in liquid nitrogen vapor before cryostat sectioning for enzyme histochemistry?

Answer: To achieve rapid freezing that preserves labile enzyme activity

Quenching rapidly freezes the tissue, which halts autolysis and preserves labile enzyme activity by preventing the chemical and thermal degradation that occurs with slow freezing or chemical fixation.