The development of the mice embryo’s heart.

ABSTRACT

Serial sections of 4-6 mm mice embryos were carefully studied in relation to the serial sections of 10 mm pig embryos under a light microscope to compare the development of the heart and related blood vessels. The heart of a 4-6 mm mouse embryo has incompletely divide chambers comprising two atria and two ventricles. The partition of the atrium, i.e. the septum primum, begins to from at the 4 mm stage and two ventricles. The partition of the atrium, i.e. the septum primum, begins to from at the 4 mm stage and completely attaches to the endocardial cushion at the 6 mm stage. The rupture of the septum primum brings about communication between the two atria, the foramen secundum. Communication between the two ventricles is also by the interventricular foramen. The right atrium receives venous blood from the right horn of the sinus venosus, which is larger than that of the left side. The bulbus cordis communicates with the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the dorsal aorta. The heart of 4-6 mm mice embryos is highly similar to that of a 10 mm pig embryo. Since mice embryos are very easy to obtain for slide preparation, there would be no problem in using mice embryos instead of pig embryos for the study of the development of the heart.