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All of the blood cells in the human body are produced in the bones, inside the bone marrow.

Bone Marrow is produced in bones
Stem Cells form in bone marrow

Bone marrow looks like a network of tiny little connected caves, similar to a honeycomb. Inside are very special parent cells called stem cells. A stem cell can divide itself and produce a twin. This process of cell division is called mitosis. Through mitosis, the stem cell can keep on creating more and more stem cells just like itself.

Process of Cell Division or "Mitosis"

The stem cell can develop into all the other different blood cells as well! The stem cell can actually "differentiate" into red cells, white cells and platelets!

Here is a look at how a stem cell differentiates into a red cell: inside the cell, a structure called the nucleus, acts like a computer program.


It directs the cell to produce a special protein called hemoglobin. The hemoglobin makes red cells look red and gives them the ability to attract and transport oxygen.


After the red cell is full of hemoglobin, the job of the nucleus is done and it gets kicked out. Then, the mature red cell has a little dip in its middle on both sides.


At this point, the red blood cell leaves the bone marrow and begins to circulate in the bloodstream.


Through mitosis, stem cells can also become many different kinds of white cells.


White cells are an extremely important part of your immune system because they guard the human body against infections and diseases.


Stem cells can also become platelets. The stem cell turns into a factory cell called a megakaryocyte. This is a very large cell with several nuclei.


The megakaryocyte never leaves the bone marrow, but does produce many, many fragments. These fragments are actually the platelets: small pieces of cell material or cytoplasm. They leave the bone marrow and circulate freely in the bloodstream.


In addition to continuing to produce all the cells in the human body, stem cells are also extremely important in medicine and research.


People who need a bone marrow transplant because they are ill with a disease such as leukemia or cancer, may receive new stem cells from the healthy bone marrow of a volunteer donor through a transfusion.


It is hoped that with this treatment, their own bodies will begin producing a healthy variety of blood cells again.

When a bone marrow transplant does take place, it is only the liquid part of the marrow that is donated, not the bone.


Some words I got from the movie are platelets, plasma, bone marrow stem cell mitosis, nucleus, oxygen and fibrin.
— Susanna,
elementary school student
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