DNTT and hydrops fetalis: 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).