Direct Observations on the Mode of Invasion of Living Tissues by Ice. Part I. The Mode of Propagation of Ice in the Course of Freezing of Living Tissues. Part II. Behavior of Cells Upon Encounter with Invading Ice During Freezing of Living Tissues

摘要

Direct observations, during freezing, of pieces of frog tissues or organs (mesentery, nictitating membrane, lung, pericardium and muscle) were made by means of the apparatus for cryomicroscopy. Three stages in the ice invasion of tissues were noted: (1) Superficial freezing: at high subzero temperatures, a flimsy blanket of ice spread over and underneath the thin layer of tissue. (2) Intercellular freezing: at slightly lower temperatures, ice from the superficial layer was seen to spread between the cells, the advancing ice front sometimes using tissue elements, like bundles of collagenous fibers, as pathways. (3) Intracellular freezing: at still lower temperatures, ice entered the cells; the red blood cells were seen to freeze individually. Shrinkage by osmotic dehydration, in extracellular freezing, was observed in erythrocytes, macrophages and muscle fibers. Ciliary activity (on peritoneum), which was not irreversibly affected by extracellular freezing, was never resumed after intracellular freezing. (Author)