The central opening formed by perforations in the septum primum is called which structure?

Prepare for the Fetal Echocardiography Test. Utilize flashcards and multiple-choice questions that come with hints and explanations. Ace your exam preparation!

During atrial septation, the septum primum grows toward the endocardial cushions. Initially an opening, the ostium primum, lies between its edge and the cushions. As the septum primum fuses with the cushions, this ostium primum closes. Simultaneously, perforations appear in the upper part of the septum primum and coalesce to form a single, larger opening called the foramen secundum. This is the central opening created by those perforations, allowing continued flow between the atria in fetal life. The foramen ovale then develops as the septum secundum forms to the right of the septum primum, creating a valve-like passage that shunts blood from right to left before birth.