Normal Development of the Heart

Recent advances have clarified the understanding of normal cardiac development, making it possible also to interpret the findings so as to appreciate the abnormal steps leading to congenital cardiac malformations. The appreciation of these changes has now been greatly facilitated by the reconstruction of a series of human embryos, which span the period during which the components of the heart first appear, extending to the time at which the embryonic interventricular communication is closed. In this chapter, we demonstrate these changes, combining the information obtained from the reconstructions with images available from serially sectioned human embryos and additional embryos processed so as to produce three-dimensional datasets that can be sectioned in planes to match both the histological sections and the reconstructions.