Olfactory mitral cell integrity after freeze-fixation.

The condition of freeze-fixed mitral cells from the main olfactory bulb of the rat brain was found to depend on the rat at which the tissue is frozen: at very slow rates, mitral cells swell and rupture; at faster rates, cell integrity is preserved. Cooling the tissue to just above its freezing point before rapid freeze-fixation helps to maintain cell integrity at depths well below the surface. When freeze-fixation must be used, as in the 2-deoxyglucose technique, rapid freezing rates should be used to minimize diffusion of isotope and increase autoradiographic resolution. After rapid freezing, better cell integrity was produced by freeze-drying and plastic embedding than by cryostat sectioning and thaw-mounting.