Fig. 5. Expression of Igfbp5 in the hair follicle reduces the number of medulla columns. Transgenic expression of Igfbp5 in hair follicles during the growth phase using the involucrin promoter decreases the length of hair shafts (top) and reduces the number of air space columns to one (bottom). The extraordinary thinness of hair shafts severely hampered the isolation of intact hairs. Thus, the presence of auchene hairs could not unequivocally be confirmed.