Figure 2.

Induction of the anagen progression by hair plucking in Stat3^−/− mice as well as controls. Hair in the back was plucked at PND 45, which is during the second telogen. Approximately 10 days later, hair emerged from the skin surface in both Stat3^{+ /+} and Stat3^−/− mice (data not shown). Histological anagen stage, characterized by the appearance of thick and elongated follicles in deep adipose tissue, was demonstrated in both Stat3^+/+ and Stat3^−/− mice at day 12 after plucking (Middle and Bottom of PND 57). Follicles of Stat3^+/+ and Stat3^−/− mice were equally in late anagen at PND 66 (day 21 after plucking), as shown by their shortening and partial shrinkage in the dermis. Meanwhile, untreated control mice (Stat3^+/+) remained in telogen (Top), in which untreated Stat3^−/− mice likewise remained in telogen (data not shown for simplicity). (Bar = 300 μm.)