Development of heart

Prior to looping, the acellular space between the myocardium and endocardium in the heart is filled with a deformable extracellular matrix, the cardiac jelly, secreted by the myocardium. Radioactive labeling demonstrates that proteins produced in the myocardium flow toward the endocardium and are incorporated into the basal lamina. 

C i.e. Myocardium 

Dorsal mesocardium forms transverse pericardial sinus; somatopleuric mesoderm forms parietal pericardium; splanchnopluric mesoderm forms myocardium & conduction system of hearts (i.e. Purkinje fibers) Q; neural creast cells form subpulmonary infundibulum.

Cardiac jelly forms endocardial cushion and myocardium

Ans. B: Septum primum

Fossa ovalis and anulus ovalis lie on the atrial septum, which separates the right atrium from the left atrium.

The fossa ovalis is a shallow depression, which is the site of the foramen ovale in the fetus.

The anulus ovalis forms the upper margin of the fossa.

The floor of the fossa represents the persistent septum primum of the heart of the embryo, and the anulus is formed from the lower edge of the septum secundum

Ans. is ‘d’ i.e., Subcardinal vein 

Sinus venosus : It is the caudal most part of tubular heart. At its lower end it presents right and left horns. Each horn receives blood from following three veins :

1. Vitelline vein from yolk sac. Right vitelline vein forms terminal part of interior vena cava.
2. Umbilical vein from placenta.
3. Common cardinal vein from body wall. Right common cardinal vein forms superior vena cava.