Embryological Development
During development, the atria initially share a common chamber. As the two begin to separate, the septum is not fully formed to allow blood shunting from the right to left atrium in order for blood to bypass the lungs. The septum primum and spina vestibuli grow together to divide the right and left atria during the fifth week of development. This results in the formation of the foramen primum. The septum primum will continue to grow until the sixth week when the dorsal and ventral cushions will fuse to form the atrioventricular septum. The fusion process closes the foramen primum via controlled cell death (apoptosis) and several smaller perforations come together to form the foramen secundum. The perforations form before the foramen primum closes completely, ensuring the shunting process continues at all stages.
Read more about this topic: Foramen Secundum
Famous quotes containing the word development:
“The man, or the boy, in his development is psychologically deterred from incorporating serving characteristics by an easily observable fact: there are already people around who are clearly meant to serve and they are girls and women. To perform the activities these people are doing is to risk being, and being thought of, and thinking of oneself, as a woman. This has been made a terrifying prospect and has been made to constitute a major threat to masculine identity.”
—Jean Baker Miller (20th century)