This book is unique. It deals primarily with and brings together a wide-ranging group of essays spanning more than half a century s worth of research done by Bernard G Sarnat. Much of this historical review remains significant and germane today. Some material antedates the emergence of the specialties of craniofacial biology craniofacial surgery and bone biology while many of the reports preceded the period of molecular biology. This book thus represents a fundamental pioneering contribution to a representative portion of the specialties.Building on past data reported by Sarnat James P Bradley contributes significantly to the present by including recent works which cover issues dealing with stem cell tissue regeneration and tissue engineering research. In addition appropriately selected clinical work is included -- a result of the further development and maturity of the specialties. And what does the future hold? No doubt unpredictable gigantic advances.The purpose of this selective organized and limited review analysis and summary of personally conducted experiments is to relate certain aspects of differential growth and change and nonchange to age sites rates factors and mechanisms. In many instances correlations are made between research findings and clinical practice and this retrospective study brings all of them together.