[Human cardiac development: total volumetric increase of the heart, ventricular myocardium and endocardial cushions during the embryonic period].

Purpose: To compare the volumetric growth of the whole heart (WH), ventricular myocardium (VM), and endocardial cushions (EC) among each other and in relation to the growth of the embryo.
Patients and Methods: Collection of human embryos serially sectioned and stained (27 embryos) in post-somitic period. The volumes of WH, VM and EC were morphometrically determined and statistically correlated to the embryo's crown-rump length (C-R) by using the allometric equation Y = a chi b.
Results: The cardiac growth, and the growth of the VM and EC, presented significant (p less than 0.01) but allometically negative correlations in relation to C-R length. It indicates that cardiac changes in shape are more pronounced than in size. However, relative to the heart itself VM is the component that presents greater volumetric increase during the second month of gestation. EC decreases and end the embryonic period proper with less of 3% of the cardiac volume.
Conclusion: Our quantitative results agree with more recent morphological studies which consider EC with small significance in valves and septa development, probably functioning more as a plastic component than in genesis of cardiac structures. On the contrary some lack in growth of the VM should disturb deeply cardiac development.