What is the Difference Between Septum Primum and Septum Secundum?

The septum primum and septum secundum are two structures that play crucial roles in the development of the heart. They are part of the atrial septum, which divides the left and right sides of the heart. Here are the key differences between septum primum and septum secundum:

1. Location: The septum primum is located on the left side of the heart, while the septum secundum is located on the right side of the heart.
2. Development: The septum primum develops at the end of the fourth week of fetal development, while the septum secundum develops at the end of the fifth week or the beginning of the sixth week.
3. Structure: The septum primum is thin and comprises a crescent-shaped membrane that grows down from the top layer of the heart. In contrast, the septum secundum is a muscular flap-like structure that is important in the closure of the foramen ovale.
4. Function: The septum primum allows blood to flow from the right side to the left side of the heart during fetal development. The septum secundum is essential in the closure of the foramen ovale in the fetus after birth, as it fuses with the septum primum to form the interatrial septum.

In summary, both septum primum and septum secundum are important structures in the development of the heart, with the septum primum being a thin, crescent-shaped membrane and the septum secundum being a muscular flap-like structure. They play different roles in the heart's development, with the septum primum allowing blood flow between the heart's sides during fetal development and the septum secundum being crucial for the closure of the foramen ovale after birth.

Comparative Table: Septum Primum vs Septum Secundum

The septum primum and septum secundum are two structures that play important roles in the development of a fetus's heart. Here is a table comparing their differences:

Both septum primum and septum secundum are crucial for the proper development of a fetus's heart. Defects in the fusion of these structures can lead to atrial septal defects (ASD).