Ultrastructural changes in the microvasculature following cryosurgery of oral mucosa

Ultrastructural studies on vessels in oral mucosa subjected to surface freezing were carried out. Only minor changes were visible in the first 30 mins. post operatively but after this time both capillaries and venules were involved in a delayed prolonged response which was similar in character to that following certain other stimuli but which had some unique characteristics. The deposition of carbon in these experiments was compatible with increased permeability of the vessels and the ensuing lack of carbon labelling was shown to be due to the onset of platelet thrombosis. Structural endothelial damage was produced following the freezing episode and occurred prior to the time expected if anoxia were the reason for the vessel damage. There was no evidence that the presence of ice crystals during freezing produced direct rupture of vessels.