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 tubercles 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. 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 tubercles 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. Relationship of the Development of the Ventricular Septum to the Position of Ventricular Septal DefectsCHESTVol. 58Issue 5PreviewIt is refreshing to read the articles in this issue of CHEST by Drs. Goor, Edwards, Lillehei and Rees (see pages 453 , 468 ) on the development of the ventricular septum and on the position of isolated ventricular septal defects anatomically and embryologically. These communications enhance the literature on congenital heart disease. It is of significance that these reports come from pathologic and surgical laboratories rather than from an anatomic or embryologic laboratory. The pathologist and surgeon are confronted with the data of congenital heart disease, and it is these data which send them to their embryologic sources for their explanation. Full-Text PDF