Bone Marrow Stem Cells: Biology School Project

[Mohamad&Issa]

Hello...
For my biology school project, I was searching throw internet about Stem Cells in the bone marrow, that are responsible for the renewal of blood cell.
I found that the bone marrow stem cells transform into red blood cells, white blood cells, monocytes...
My question is how can this cells be transformed into different cells? And what takes place inside the cell? Also who it would produce a specific amount of each cell?

 

[Pythagorean]

Differentiation occurs as a result of cues in the local cellular environment, typically from molecules called "growth factors". It often results in a change in gene expression and cytoskeleton signals to change the morphology of the cell (like radial glia are long spindly cells that eventually differentiate into star-shaped astrocytes; this requires a lot of changes in cytoskeletal structure.)