Preface [Hot Topic: Recent Advances in Developmental and Reproductive Toxicology (Executive Editor: Gian Mario Tiboni)]

Developmental toxicology is primarily concerned with adverse effects of environmental and therapeutic exposures to the unborn child. This is the second issue of Current Pharmaceutical Design to focus on this important and controversial area. In line with the previous issue, the emphasis of this set of articles is to discuss emerging aspects in the field. Vitamin A metabolites, and particularly retinoic acid, are essential for normal embryonic development and alteration of retinoid signalling can result in severe dysmorphogenesis of almost all organ systems. In their paper Lee, Kochhar and Collins [1] discuss the phenotypic features, pathogenesis and molecular bases of retinoid-induced limb teratogenesis. The article also provides the reader with a description of normal limb development. Among birth defects, cleft palate is one of the most common. Greene and Pisano [2] offer an up-to-date discussion on the role of growth factors in normal and abnormal orofacial development. Major consideration is given to the transforming growth factor gene family. Folate metabolism represents a major area of research in developmental toxicology. The article by Brauer and Tierney [3] covers the recent developments regarding the impact of elevated homocysteine on morphogenesis of neural tube and neural crest cell-derived structures. There is an intensive search for alternative tests to in vivo animal models in developmental toxicity testing. In the article authored by Bremer and Hartung [4], the reader is provided with an overview of the current status of in vitro test development. The use, limitations and further needs of embryonic stem cell assays, one of the most promising models, are illustrated. Phytoestrogens are plant-derived isoflavonoids and lignans with estrogen-like activities. The article presented by You [5] reviews recent findings on the developmental effects of genistein, one of the most important phytoestrogens. The article also describes the potential of genistein to alter the toxicological response to the pesticide methoxychlor. The last manuscript, from Clementini and myself [6], focuses on the recently evolving topic of the teratological consequences of nitric oxide synthesis inhibition. I would like to express my sincere appreciation to the contributors.