A 12-year-old boy is rescued 2 days after becoming lost in the Canadian woods in February. Physical examination shows he has gangrene of his fingers and toes. Which of the following mechanisms of cell injury played the most important role in mediating necrosis in the fingers and toes of this patient?

Exposure of the extremities to severe cold results in the crystallization of tissue water, which causes cellular disruption and vascular changes, resulting in frostbite. Localized thrombosis often leads to focal ischemia and gangrene of toes and fingers. Mechanical disruption of cellular membranes by ice crystals occurs during both freezing and thawing. The other choices are associated with cell death, but they are not early events in frostbite-induced necrosis.Diagnosis: Frostbite