Sup. vena cava 



Aorta 



Pulmonary trunk 



DEVELOPMENT OF THE HEART 



Septum II Foramen ovale 



255 



Septum T 



Inferior vena can 



L. atrium 



FIG. 264. Lateral dissection of the heart of a 65 mm. human fetus, viewed from the left side, 

 showing the septa and the foramen ovale. X 8. 



Put. a. 



Sept. II f 



L. vent. 



A B 



FIG. 265. Lateral dissections of the human heart, viewed from the left side: A, from a 

 22 mm. embryo; B, from a 105 mm. fetus. Bic. va., Bicuspid valve; Cor. sin., coronary sinus; 

 For. ov., foramen ovale; I.v.c., inferior vena cava; L. atr. vent, c., left atrio-ventricular canal; 

 L. vent., left ventricle; Put. a., pulmonary artery; Sept. I, Sept. II, septum'pritnum and septum 

 secundum. 



