The subcutaneous injection of TNF (200 ng of recombinant mouse TNF-α in 50 μl of Matrigel) induced HF TAT in both refractory (7-week-old) and competent telogen (9-week-old) mice at the injection site, with more TAT HFs observed in the 9-week-old mice (∼5,000 anagen HFs) than in the 7-week-old mice (<2,000 anagen HFs) (Fig. 3a,b), consistent with the findings of a recent study14. Here, TNF is linked to hydrops fetalis.