amnion brain oropharyngeal membrane notochord pericardial cavity heart tube septum transversum foregut heart tube pericardial cavity B septum transversum oropharyngeal membrane foregut heart septum transversum pericardial cavity
pericardial coelom neural groove level of section B neural fold mesenchyme dorsal aorta amnion- reg pericardial coelom. yolk sa primitive streak endocardial heart tube dorsal neurol groove neural tube mesocardium dorsal aorta pericardial cavity fusing endocardia heart tubes endocardial heart tube cardiac jelly- yolk sac meeardo D parietal pericordium pericordium truncus arteriosus level of section F endo- dorsal aorta- cardium .remnant of mesocardium Transverse sinus of pericardium sinus venosus bulboventricular loop atrium heart wall- pericordiol cavity cut edge of parietal pericardium chest wall. epicardium
arterial end of heart Ist oortic arch splanchnic mesoderm (二)心脏外形的建立 using heart tubes unfused heart tubes septum frdnsversum venous and of heart Ist aortic arch 心管形成三个膨大：心球、 心室和心房。以后心房尾端 ventricle 又出现静脉窦。 ￥心管发生S形弯曲。 truncus arteriosus bulbus cordis ventricle atrum sinus venosus septum transversum truncus arteriosus bulbus cordis ventricle common cardinal vein umbilical vein telline vein
（二）心脏外形的建立 心管形成三个膨大：心球、 心室和心房。以后心房尾端 又出现静脉窦。 心管发生S形弯曲
Aortic roots Pericardium Bulbus cordis Pericardial cavity Bulboventricular sulcus- -Ventricle Atrium Sinus Sinus venosus venosus 父三《