Quantifying heart development

This thesis presents a series of papers on quantified heart development. It contains an atlas of human embryonic heart development, covering the first 8 weeks after conception. This atlas gives graphs of growth in size and volume of the various cardiac compartments. Such measures are still scarce in literature as illustrated in a review about ventricular wall development. The atlas also shows that by quantification of growth, new insights in developmental processes, such as sinus venosus incorporation can be gained. It, together with a series of ventricular wall growth curves covering foetal development, illustrates that a hypertrabeculated ventricle is the result of differential growth rather than a failure of compaction as has been presumed to underlie left ventricular non-compaction cardiomyopathy. Additionally, this thesis shows that trabecular myocardium is not necessarily weaker or ill-adapted to force generation compared to the compact wall as is assumed to be the case in aforementioned cardiomyopathy. Furthermore, quantification of atrioventricular canal growth on foetal ultrasounds lend support to the theory that aberrant atrioventricular canal development can lead to tricuspid valve agenesis. Finally, this thesis shows that there is a role for comparative anatomy, in a broader sense than just mouse and chicken, in understanding mammalian and human heart development by comparing a series of bird hearts from different species.