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Show MORPHOLOGICAL ANALYSIS OF CARDIAC DEFECTS IN NEURAL CREST DEFICIENT ZEBRAFISH EMBRYOS Cardiac neural crest consists of multipotential precursor cells that give rise to cardiac outflow tract septation, pharyngeal arches, and thymus in chicks and mice. We have recently found that cardiac neural crest cells differentiate into cardiomyocytes in zebrafish. To understand the contributions of neural crest to heart structures, we have analyzed heart structures in two models of neural crest deficient zebrafish: embryos injected with semaphorin3D (sema3D) anti-sense morpholino (MO) and acelebullar (ace) mutant embryos. Zebrafish embryos (72 and 96 hours post fertilization) were plastic embedded, sec- tioned at 5-6 urn, and stained with Hematoxylin and Eosin. sema3D MO embryos had defects in caudal pharyngeal arch and thymus development, reflecting neural crest defects. sema3D MO hearts were dys-morphic with hypertrophic cardiomyocytes in the ventricle. The cardiac ventricle in ace mutants was smaller and had fewer cardiomyocytes. This analysis indicates that two neural crest deficient models, sema3D MO embryos and ace mutants, have distinct heart defects. This suggests that different populations of neural crest cells have distinct roles in cardiac development. An my Iran Junior Biological Chemistry anmy.tran@hci.utah.edu Faculty Sponsor: H. Joseph Yost Depts. of Oncological Sciences & Pediatrics Joseph.Yost@hci.utah.edu Faculty Sponsor: Mariko Sato Huntsman Cancer Institute 73 |