INCORPORATION OF TRITIATED THYMIDINE INTO THE SKIN AND HAIR FOLLICLES

Diurnal fluctuations in incorporation of tritiated uridine and tritiated thymidine are reported for full thickness skin and its two proliferative populations, the epidermal basal layer and the hair follicle germ or matrix. Recently developed techniques whereby these two populations can be studied independently were utilized. Resting (unplucked) skin and skin in the middle of the hair growth cycle (10 days after plucking) was studied. the diurnal fluctuations differed at these two stages of the hair cycle. Generally a single minimum level of activity was observed shortly after the beginning of the dark period of the day, i.e. after 18.00 hours.