Teratogenic and lethal effects of 2-24 h hyperthermia episodes on chick embryos

Hyperthermia is a proven teratogen, inducing malformations and embryonic death in humans as well as in laboratory animals. The aim of our study was to define temperatures that are teratogenic after short-term exposure (from 2 to 24 h) on embryonic days 1-7 and to detect critical periods for the origin of structural defects in the chick embryo. Hyperthermia of 41 degrees C was not embryotoxic, temperatures from 42 to 44 degrees C induced malformations and embryonic death, while nearly all embryos died even after the shortest exposures to 45 or 46 degrees C. Among the wide spectrum of observed malformations, only ventricular septal defect (VSD) and caudal regression syndrome(CRS) were present at frequencies significantly different from those seen in controls. (c) 2007 Elsevier Ltd. All rights reserved.