Here's a breakdown:

* Diaphysis: This is the long, cylindrical shaft of a long bone.

* Yellow Marrow: This is primarily composed of fat cells and serves as an energy reserve. It also contains some hematopoietic stem cells, which are capable of developing into blood cells, but these are less active than those in red marrow.

Red marrow, on the other hand, is found in the epiphysis (the ends of long bones) and is responsible for producing blood cells.