Reply to Chi et al.

TO THE EDITOR We are grateful to Bruce Morgan and his colleagues for engaging in a dialog over our own article (Kaushal et al., 2015). We believe that open discussion about conflicting observations is important in moving forward research—far too often results that are at odds with one another are simply ignored. There are certainly aspects of the Chi et al. (2017) study that are superior to ours. In particular, we agree that there are advantages of studying the dermal papilla (DP) in unpigmented skin, and we note that the quantitation by Chi et al. is based on a larger number of hair follicles, and mice, than in our study. Chi et al. (2017) suggest that our results are due to misidentification of hair follicle types. We agree that DP size alone cannot be used to identify hair follicle type. We analyzed skin of P65 mice in which the hair follicle cycle was asynchronous so that we could report on anagen (stage IV; early anagen of the second hair follicle cycle, according to the classification of Müller-Röver et al. [2001]) and telogen follicles from the same mice. We believe that Chi et al. are looking at a later anagen stage. Given the low frequency of non-zigzag hairs in our samples, it is unlikely that they would skew our data. The tissue in our article (Kaushal et al., 2015) was not flash frozen but fixed with 4% paraformaldehyde before being cryopreserved in Optimal Cutting Temperature medium. Tissue preservation under these conditions is excellent (Driskell et al., 2012, 2013). The movies in the Supplemental Material of Kaushal et al. show that the 60-umethick horizontal whole mounts