The development of rabbit embryo’s heart : Serial sections of 4-14 mm rabbit embryos compared to a 10 mm pig embryo.

ABSTRACT

Serial sections of 4-14 mm rabbit embryos were carefully studied in relation to the serial section of 10 mm pig embryos under a light microscope in order to compare the development of the heart and related blood vessels. The heart of the 4-14 mm rabbit embryo has incompletely divided chambers comprising two atria and two ventricles. The partition of the atrium by the septum primum can be seen at the 4 mm stage and still incompletely attaches to the endocardial cushion even at the 12 mm stage. The rupture of the septum primum brings about the communication between the two atria, the foramen secundum, can be seen only at the 12 mm stage. Communication between the two ventricles is also via the interventricular foramen. The right atrium receives venous blood from the right horn of the sinus venosus which is larger than the left side. The bulbus cordis communication with the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the dorsal aorta. The heat of the rabbit embryo is very similar to that of the pigembryo. The pig embryos are easy to obtain for slide preparation, there will be no problem in using rabbit embryos for the study of the development of the heart.