What is a Bone Marrow Transplant?

What is the function of the bone marrow?
To release healthy blood cells into the bloodstream when they are required.
What are the two types of bone marrow?
Red: produces blood cells
Yellow: produces cartilage fat and bone
Looking at a healthy bone marrow vs. unhealthy bone marrow microscopically:

What is a bone marrow transplant?
A bone marrow transplant is a procedure in which healthy blood-forming stem cells are infused into your body.
Why would one need a bone marrow transplant?
There are a variety of reasons why one would need a bone marrow transplant. One of these includes treating cancers and other diseases of the blood. More specifically, bone marrow transplants treat people with leukemia or lymphoma.
What is the life expectancy after a bone marrow transplant?
70 to 90 percent with related donors
36 to 65 percent with unrelated donors
Sources:
https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/about/pac-20384854
https://www.medicinenet.com/bone_marrow_transplant_risks_survival_prognosis/article.htm