Indeed, this approach showed that the skin of aged CD4Cre R26-tdT mice contains enormous numbers of wildtype Ptch tdT+ HF compared to younger mice (Figure 3A), whereas, in the third anagen of CD4Cre R26-tdT back skin (11 weeks old), only isolated tdT+ HF were detected; the numbers of tdT+ HF increased enormously from the fourth (16 weeks old), fifth (25 weeks old) and to the ninth anagen (55 weeks old) (Figure 3A). This evidence concerns the gene PTCH1 and hydrops fetalis.