A Comparison of Methods for the Microscopic Examination of Frozen Tissue

Crystallization of water in tissue has received considerable study (Heard, 1955a, b; Maurer and Murray, 1951; Meryman, 1957; Parkes, 1957; Smith, 1961; Woodroof et al. , 1946). In many instances the conclusions concerning tissue disruption and crystal location (intra‐ or extracellular) are based on observations of specimens from which the ice crystals have been removed. The ice is usually removed by lyophilization, solvent extraction, or a combination of the two (Humason, 1962; Sass, 1961; Heard, 1955 a, b; Rapatz and Luyet, 1959). Specimens prepared in this manner contain numerous voids which, according to Parkes (1957, p. 524) “presumably represent the spaces occupied by ice crystals.” To our knowledge, no one has published information demonstrating how accurately the void spaces represent the size and location of ice crystals. The information which follows should be of some value in that respect.