title: The outflow tract of the heart--embryologic and morphologic correlations.
abstract: The separation process of the heart by which two great arteries and two outflow tracts are formed, was studied microscopically in 20 human embryos, ranging from 6 to 28 mm crown-rump length and macroscopically in eight hearts, ranging from 28 weeks of gestation to 80 years of age. The proximal (primary fold) and distal (ventriculo-arterial junction) borderlines of the outlet segment of the embryonic heart are important landmarks in this process. The remarkable, curved and twisted configuration of the ventriculo-arterial junction implies that the position of the arterial orifices, as well as the relative dimensions of the corresponding outflow tracts, are, already in a very early stage, similar to those in the fully developed heart. It furthermore implies that the separation by the aorto-pulmonary septum starts at this level and immediately involves the outlet segment where the two columns of the aorto-pulmonary septum mobilize the myocardium to form the posterior wall of the right ventricular outflow tract, rather than a septum between both outflow tracts. These findings make the morphology of the outflow tract of the normal heart comprehensible from a developmental point of view and throw a new light upon the morphogenesis of outflow tract malformations.
authors.affiliation: Department of Anatomy and Embryology, University of Leiden, The Netherlands.
authors.forename: M M
authors.initials: MM
authors.lastname: Bartelings
authors.forename: A C
authors.initials: AC
authors.lastname: Gittenberger-de Groot
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D006321:Heart / Q000033:anatomy & histology / Q000196:embryology*; D006343:Heart Septal Defects / Q000196:embryology* / Q000209:etiology / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology