Ultrastructural stereology of x-irradiated epidermis

Variations in the amount of several epidermal cell components during the process of radiation-induced acute cell death were studied following single local exposures of the tails of rats to a high dose of x radiation. The results were obtained by applying methods of ultrastructural stereology and expressed in relative and absolute volumes, surfaces, and numbers of the most important keratinocyte constituents. The increment of the nuclear volumes, the nuclear membrane surfaces the number of mitochondria, as well as an increase of the volume of filament bundles during the first 48 hr after radiation exposure, reveal an increased metabolic activity. Seventy-two hours after irradiation, this phase of cell hyperactivity is followed by a period in which the degradative phenomena become evident, i.e., an increasing mitochondrial swelling represented by an extreme increment in the volume of the average mitochondrion, the appearance of a significant amount of lipid droplets, and the cessation of protein accumulation in the form of cytoplasmic filaments. These statistically significant changes indicate that during the early stage of acute radiation reaction in the epidermis, the keratinocytes exhibit an increased activity which after 48 hr is surpassed by degenerative phenomena leading to ultimate cell death and skin ulceration