Proliferation precursors

To resolve the apparent discrepancies between the observed restricted nature of clones in vivo and the identification of proliferating precursors with multipotential capacity in vitro, it is necessary to postulate that cells with a multipotential capacity become progressively dormant in vivo, as development proceeds. This would explain why few... 

However, acquisition of neural bias is not sufficient to propel the neuroepithelial cell towards terminal neural differentiation path. However, acquisition of neural bias is not sufficient to propel the neuroepithelial cell towards A terminal neural differentiation path. Cell fate plasticity remains high and demands continuous reinforcement to proceed towards a specific differentiation path The transition from proliferating precursor cell to post-mitotic state is also a highly regulated step. Thus, proneural genes have an important role, regulating both cell cycle arrest and initiation of neural differentiation. 

During bone formation, a series of sequential changes occur in cells in the osteoblast lineage, including osteoblast chemotaxis, proliferation and differentiation, which in turn is followed by formation of mineralised bone and cessation of osteoblast activity. The osteoblast changes are preceded by osteoclast apoptosis, which may be dependent on active TGF- 3 released from the resorbed bone. This is followed by chemotactic attraction of osteoblasts or their precursors to the sites of the resorption defect. Chemotactic attraction of osteoblast precursors is likely mediated by local factors produced during the resorption process. 

Proliferation of osteoblast precursors is an important event at the remodeling site. This is also likely to be enhanced by local osteoblast growth factors released... 

Hematopoietic (blood) cells transport oxygen and carbon dioxide, contribute to host immunity, and facilitate blood clotting [1], A complex, interrelated, and multistep process, called hematopoiesis, controls the production as well as the development of specific marrow cells from immature precursor cells to functional mature blood cells. This well-regulated process also allows for replacement of cells lost through daily physiologic activities. The proliferation of precursor cells, the maturation of these into mature cells, and the survival of hematopoietic cells require the presence of specific growth factors. 

Lymphocytes, inflammatory cells, intestinal mucosal cells, cartilage cells and bone precursor cells Inhibition of proliferation... 

In spite of the above-mentioned similarities between basophils and mast cells, they differ in many other aspects [1,2]. Basophils complete their differentiation within the bone marrow, and mature basophils circulate in the peripheral blood and do not usually infiltrate into peripheral tissues unless inflammation takes place. Mast cells originate from hematopoietic cells in the bone marrow as do basophils, but they mature in peripheral tissues after their bone marrow-derived precursors enter the circulation and migrate into peripheral tissues. Mature mast cells reside in peripheral tissues and do not usually circulate in the peripheral blood. The lifespan of basophils is very short (several days), in contrast to that of mast cells (weeks to months). Basophils do not proliferate once they terminally differentiate whereas mature mast cells keep potential to expand in response to various stimuli. These differences between basophils and mast cells, including distinct anatomical localization, suggest their differential roles in vivo. 

Kadi L, Selvaraju R, de Lys P, Proudfoot AE, Wells TN, Boschert U (2006) Differential effects of chemokines on oligodendrocyte precursor proliferation and myelin formation in vitro. J Neuroimmunol 174 133-146... 

Robinson S, Tani M, Strieter RM, Ransohoff RM, MiUer RH (1998) The chemokine growth-regulated oncogene-alpha promotes spinal cord oligodendrocyte precursor proliferation. J Neurosci 18 10457-10463... 

O The acute leukemias are hematologic malignancies of bone marrow precursors characterized by excessive production of immature hematopoietic cells. This proliferation results in a large number of immature cells (blasts) appearing in the peripheral blood and bone marrow causing failure of normal hematopoiesis. 

O The acute leukemias are diseases of bone marrow resulting from aberrant proliferation of hematopoietic precursors. The hallmark of these malignancies is the leukemic blast cell, a visibly immature and abnormal cell in the peripheral blood that often replaces the bone marrow and interferes with normal hematopoiesis. These blast cells proliferate in the marrow and inhibit normal cellular elements, resulting in anemia, neutropenia, and thrombocytopenia. Leukemia also may infiltrate other organs, including the liver, spleen, bone, skin, lymph nodes, and central nervous system (CNS). Virtually anywhere there is blood flow, the potential for extramedullary (outside the bone marrow) leukemia exists. 

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