Response to ultraviolet radiation: ear swelling in hairless mice.

Ear swelling, as measured by an engineer's micrometer, shows a positive relationship to doses of ultraviolet radiation (over a range of 0 to 7.4 times the minimally damaging dose) during the first 4 d after irradiation. Subsequently, doses greater than 3 D (see text) caused significant thickening associated with scab formation. Doses of 3 D and lower continued to show a well-correlated dose-response to the end of the study. Changes in ear thickness afford a metric indication (non-invasively and repetitively) of the severity of a skin response to UV.