The shape of the heart in a transverse section depends on the specific level at which the section is taken. However, in general, a transverse section of the heart will reveal a roughly circular shape.

Here's a breakdown:

* At the level of the atria: The section will show the two atria, with their thin walls, separated by the interatrial septum.

* At the level of the ventricles: The section will show the two ventricles, with their thicker walls, separated by the interventricular septum.

* At the level of the valves: The section will reveal the various valves, including the mitral valve and the tricuspid valve, depending on the specific level.

Remember, the shape of the heart in transverse section is not perfectly circular, but rather a complex arrangement of chambers, walls, and valves. The exact shape will depend on the specific level of the section.