ABSENCE OF CORRELATION BETWEEN TRANSIENT CRANIAL HEMORRHAGES AND CONGENITAL-MALFORMATIONS FOLLOWING NEURAL CREST ABLATION IN CHICKS

Ablation of premigratory cardiac neural crest has been used to produce and study extensively a model of abnormal cardiovascular dysmorpholog y. Previous and continuing research in this laboratory concerns differ ent aspects of the involvement of cranial neural crest in the developm ent of cranial, cervical and cardiac tissues in chick embryos. Recentl y, we detected the occurrence of transient cranial hemorrhages 24-48 h r after the ablation of selected segments of premigratory cranial neur al crest. Since one possible mechanism of action for certain teratogen s involves nonreparable damage to a primordial embryonic tissue by an antecedent hemorrhage, the objective of this study was to determine wh ich of three different neural crest ablations is associated with hemor rhages and whether subsequent congenital abnormalities were correlated with the ablation procedure and/or hemorrhage. Premigratory neural cr est was ablated from 3 different sites, designated cardiac, mesencepha lic and trunk crest, respectively, of stage 8-10 chick embryos. Sham-o perated embryos were controls. At 24, 30, and 48 hr after ablation, ea ch embryo was observed for the presence of hemorrhages. On incubation day 11 all the living embryos were killed, fixed, weighed, and analyze d for selected length measurements, developmental stage, and the types and rates of congenital abnormalities. Cardiac and mesencephalic abla tion group embryos exhibited significant incidences of cranial hemorrh ages and changes in many of the parameters analyzed. It was concluded that the cardiac and mesencephalic, but not the trunk neural crest obl ations, produced significant changes in incubation day 11 embryos. How ever, there was no correlation between the abnormalities and the prior occurrence of the transient cranial hemorrhages. (C) 1996 Wiley-Liss, Inc.