Cell Differentiation

Table 15-11 presents a menu of regulatory factors that are involved in the process of hematopoiesis. A simplified scheme of hematopoietic cell differentiation is presented in Figure 15-21, including an indication of the site of action of the hormones and cytokines. The process of hematopoiesis has its origin in a single small population of self-renewing pluripotent stem cells that can be stimulated to differentiate along one of four general pathways; these include (a) the production of the antibody-generating cells the B and T lymphocytes, which are stimulated by interleukins 1-7; (b) the production of the white blood cell line, including monocytes, granulocytes, and macrophages whose collective production is largely stimulated by the family of colony-stimulating factors; (c) the production of platelets, which is promoted by several cytokines and hormones including erythropoietin; and (d) the production of the red blood cells, which is largely stimulated by erythropoietin.

The stem cells appear to require exposure to multiple cytokines to initiate the cell-differentiative process to create committed stem cells. It should be appreciated that although Figure 15-22 and Table 15-11 imply a linear cell differentiation process along precise pathways with precise locations for effects of the cytokines and growth factors, the in vivo reality is believed to be considerably more complex; e.g., there are no examples where one cytokine or regulatory action is confined to cells of a single hematopoietic lineage.

A detailed consideration of the complexities of the hematopoietic process is beyond the scope of this presentation; however, a brief discussion of the various classes of growth factors and hormones is presented in the following.

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Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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