In the last fifty years dramatic progress has been made in the under­ standing of skin and skin diseases. Although we are still someway off understanding the ultimate causes of such disorders as psoriasis, atopic dermatitis and the congenital disorder of keratinization, we now have considerable information on the physiological disturbances in various diseases. This has permitted and encouraged a rational approach to treatment. The successful use of antimitotic agents, immunomodulators and retinoids may be cited as examples. A major reason for this im­ provement may be the fact that researchers accept models for the in­ vestigation of skin diseases. Increasing numbers of them have become available in the past years. So many have been described that it is doubtful whether anyone researcher is aware of all the other models described - even in his own field of interest. This book is a challenge for those involved in the study of skin and its disorders to use the sundry models of skin that have proven helpful. It would be impossible for this work to be all-embracing but it is hoped that the choice of models offered in this publication will be stimulating and helpful in the solution of knotty skin questions. April,1986 Ronald Marks, Cardiff Gerd Plewig, DUsseldorf Table of Contents In Vivo Models Human Model for Acne . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 L. C Brummitt, W. J. Cunliffe, G. Gowland Models to Study Follicular Diseases l3 G. Plewig Models for Wound Healing. . . . . . . . . . . . . . . . . . . . . . . . . 24 R. Marks, D. Williams, A. D.