Measurement of the time between synthesis and surface excretion of sebaceous lipids in sheep and man.

The delay between synthesis and excretion of sebum in sheep and in man was determined by measurement of the time between intradermal injection of (1"C ]acetate and the appearance of a peak of radioactivity in the skin surface lipids at the injection site. In two sheep, a peak of radioactivity in the total surface lipid occurred 6 days after injection, and this is interpreted as the time required for the excretion of sebum after it was synthesized. In three human males, the delay between synthesis and excretion averaged 8.0 ± 0.5 days. Fractionation of the surface lipids from both sheep and man showed that each of the major constituents had a similar excretion time.