During atrial septation, the septum primum grows downward from the roof of the atrium, leaving a temporary opening beneath it. What is the name of this opening?
- A Ostium secundum
- B Foramen ovale
- C Ostium primum ✓
- D Ductus arteriosus
Correct answer: C. Ostium primum
Explanation
The ostium primum is the space between the growing septum primum and the endocardial cushions. It closes when the septum primum fuses with the cushions. The ostium secundum forms within the septum primum, and the foramen ovale is the opening between the septum primum and septum secundum.
Reference: Langman's Medical Embryology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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