The development of the interventricular septum of the human heart; correlative morphogenetic study.

For the understanding of the developmental significance of various parts of the normal ventricular septum, 54 normal human embryos and 154 mature heart specimens showing different types of VSD’s and AV canal malformation were studied. The pars interventriculare of the septum membranaceum is derived primarily from the right superior and inferior tubercies of the AV cushions. The pars atrioventriculare is formed by the closure of the bulboauricular canal. The posterior smooth septum is a result of the balanced growth of the margins of the interventricular foramen. The posterior trabeculated septum develops as a result of the expansion of the two ventricles on both its sides. The anterior portion of the crista, the conoventricular septum, is derived from the anterior portion of the conoventricular flange. The midportion of the crista represents the conus septum and it is derived from conus ridges 1 and 3. The parietal portion of the crista is derived from conus ridge 3.