MOLECULAR HISTOLOGY IN SKIN APPENDAGE MORPHOGENESIS

Classical histological studies have demonstrated the cellular organiza tion of skin appendages and helped us appreciate the intricate structu res and function of skin appendages. At this juncture, questions can b e directed to determine how these cellular organizations are achieved. How do cells rearrange themselves to form the complex cyto-architectu re of skin appendages? What are the molecular bases of the morphogenes is and histogenesis of skin appendages? Recently, many new molecules e xpressed in a spatial and temporal specific manner during the formatio n of skin appendages were identified by molecular biological approache s. In this review, novel molecular techniques that are useful in skin appendage research are discussed. The distribution of exemplary molecu les from different categories including growth factors, intracellular signaling molecules, homeobox genes, adhesion molecules, and extracell ular matrix molecules are summarized in a diagram using feather and ha ir as models. We hope that these results will serve as the ground work for completing the molecular mapping of skin appendages which will re fine and re-define our understanding of the developmental process beyo nd relying on morphological criteria. We also hope that the listed pro tocols will help those who are interested in this venture. This new mo lecular histology of skin appendages is the foundation for forming new hypotheses on how molecules are mechanistically involved in skin appe ndage development and for designing experiments to test them. This may also lead to the modulation of healing and regeneration processes in future treatment modalities. (C) 1997 Wiley-Liss, Inc.