Correlation of the dermal microvasculature morphology with the epidermal and the endothelial population changes produced by single X ray fractions of 1649, 2231 and 2619 rad in swine

Abstract

The role of the dermal microvasculature in the production of skin changes has not been specified. The healing moist reaction observed between 21 and 36 days following X ray exposures of 1649, 2231, and 2619 rad results from the loss and repopulation of the epidermal basal cells. The second breakdown occurring between 36 and 70 days results from the loss of endothelial cells in vessels of the papillary plexus. The epidermal population in swine skin decreases linearly to a nadir at 23 days and returns to control levels (and beyond) exponentially at 28-32 days. During this period, the endothelial cell density remains at control levels. At 28-36 days there is an abrupt decrease to 50% of control levels following administration of 1649 rad and a further decrease to 0 after 2231 and 2619 rad by 70 days. The qualitative morphology of the microvasculature remains unchanged until 32-36 days following irradiation. At that time there is increased endothelial cell pyknosis and loss of endothelial cells. A decrease in the vascular lumen cross-section profile density occurs by 43-49 days. This is accompanied by a progressive vascular dilatation. Interstitial edema becomes marked, with an inflammatory infiltrate of varying amount. Micro thrombi are found after 2619 rad, but are nearly absent after 1649 rad.