Cryostat: A chamber that can maintain very low temperatures. Medical laboratories use a cryostat to preserve frozen tissue samples while a microtome, an extremely sharp cutting instrument mounted inside cryostats, slices the tissue into pieces thin enough to be observed under a microscope. The sliced piece must be so thin as to look nearly transparent. A pathologist, a laboratory doctor trained to identify evidence of disease in microscopic structures, then examines the slice to confirm or rule out the presence of a disease, such as cancer. Use of frozen tissue samples enables physicians to examine tissue and diagnose its condition more quickly than if the tissue had been preserved without freezing.
Microtomes may be used alone, without cryostats, to yield thin microscopic samples.
"Cryostat" is derived from the Greek "kryos" (cold) and "statos" (standing, stationary, like the cryostat chamber). "Kryos" gives us many English words, such as "cryonics" (use of coldness in medicine to bring about beneficial results) and "cryosurgery" (use of below- freezing temperatures to destroy disease). "Statos" and related Greek words give us such English words as "static" and "stationary."