Brenda Morgan, age 10, of Newport News, Virginia, for her question:
Where does the body manufacture white blood cells?
The white cells are the policemen, the national guard and the federal troops of the blood stream. They perform dramatic deeds and their history is fascinating. Until a few years ago, they were somewhat mysterious cells but modern biologists are busy solving the last of their secrets.
There are 700 red cells to each white cell in the blood stream. And the white cell may be one of three kinds a granulocyte, a lymphocyte or a mcnocyte. Chances are, it is a granulocyte, for these white cells far outnumber the lymphocytes and monocytes. All of these white blood cells are fighters, born to defend the body from invading microbes. And their fabulous story begins in the chest region when a baby is just a few days old.
A newborn baby has a thymus gland about as big as his fisty little hand. It is shaped like a pair of sacks, handing down from his throat into his chest region. This thymus gland gets busy at once, making an assortment of very special cells. They are coded cells carry
ing patterns and blueprints. They can issue orders and other cells must obey them. Some of the special cells made in the baby's thymus gland can order the body to use its materials to build white cells and more white cells in a hurry.
The creation of these coded cells is soon finished and the thymus begins to shrink. As the child grows older, it shrinks to the size of two very small fingers. But its main work is done for those coded cells can go on repeating their built in orders throughout life and throughout life, the body must obey their orders. They leave the region of the thymus and find themselves new homes in other parts of the body.
Some settle in the fatty marrow tissues that fill the hollow centers of the bones. Some settle here and there in the lymph system that governs watery liquids through the body. Some settle in the soft spleen in the kidney region. Wherever they settle, those coded cells form small factories that manufacture useful items according to their blue prints. The body contains countless numbers of these little factories and many of them can produce at least one type of white blood cell as needed. white blood cells
Most of the granulocytes are manufactured in the fatty bone marrow. The lymphocytes are born in the cell factories of the lymph system. Monocytes may be manufactured by coded cells in the bone marrow or in the spleen. Each white cell leaves its birthplace as soon as it is completed. As a rule, it makes its way at once to the blood stream and joins the throng of circulating blood cells. Sometimes it seeps into the lymph system or hurries through the tissues to do combat in a trouble area.
Throughout its life, a white cell is a soldier of the guard, always alert and ready to do its duty to defend the body against its enemies. The granulocyte and monocyte armies can leave the blood stream and chase an enemy through cells and tissues. When a granulocyte catches a microbe, it engulfs and devours it in a few seconds.
It takes gore than 3,000 red blood cells to measure an inch and though a living cell usually has a nucleus, a red cell does not. The white cells are larger than the red cells and they do have nucleoli, though in some cases this cell core is broken into fragments. When the body is attacked by disease or infection, more white cells are made in a hurry. The number may be doubled in a few hours. This is why, when you are sick, the doctor may take a blood count. If the number of white cells is higher than normal, he knows that the extra troops have been created to cope with an invasion of germs or some other destructive enemy.