Preparation of trichogenic dermal cells for successful HF induction. a Microdissected lower portion of human HFs. The dermal papilla (DP) and the dermal sheath (DS) are respectively indicated. b High magnification image of DP and the “flipped” cup shape portion of DS. Note that two components are continuous. c In vitro expansion of human DP. d Restoration of DP properties in DP activation culture condition (DPAC). Note that DP cell morphology is distinct from that shown in (c).