Precursor cell

Hemangioblasts are the bipotential precursor cell population from which hematopoietic and angioblastic cells arise. 

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. 

NFAT2 plays a key role in the development of the embryo s heart. In the precursor cells, there is a temporal and spatial specific expression of NFAT2, which directs the formation of the valves and the septum in the heart. In the adult heart, NFAT proteins also cooperate with transcription factors of the GATA and MEF2 families to regulate cardiac muscle hypertrophic responses. 

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

The thymus is a lympho-epithelial organ, located within the upper thorax. One of its fimctions is the conversion of certain lymphoid hematopoietic precursor cells originating from the bone marrow into thymus-derived lymphocytes (T-cells). 

Griseofulvin (Grisactin) exerts its effect by being deposited in keratin precursor cells, which are then gradually lost (due to the constant shedding of top skin cells), and replaced by new, noninfected cells. The mode of action of flucytosine (Ancobon) is not clearly understood. Clotrimazole (Lotrimin, Mycelex) binds with phospholipids in the fungal cell membrane,... 

Mice exposed to 2,000 ppm of trichloroethylene, 4 hours/day for a 5-day period, had a significant increase in abnormal sperm morphology of 1% 28 days after the exposure (Land et al. 1981). No effect was seen at 200 ppm. A 6% increase in abnormal sperm was observed 4 weeks, but not 4 days or 10 weeks, after mice were exposed to 100 ppm trichloroethylene 7 hours per day for 5 days (Beliles et al. 1980). Based on the time after exposure at which sperm were affected, the study authors indicated that trichloroethylene damages sperm precursor cells but that spermatogonia were either unaffected or were capable of recovery. Reproductive performance was not tested in these studies. Another mouse study tested the effects of a 5-day exposure (6 hours/day) on spermatid micronuclei frequency no effects were observed at exposure levels of up to 500 ppm, the highest concentration tested (Allen et al. 1994). These results were interpreted as evidence that trichloroethylene did not cause meiotic chromosome breakage or loss. No treatment-related reproductive effects were seen in female rats exposed to 1,800 ppm trichloroethylene for 2 weeks (6 hours/day, 7 days/week) before mating (Dorfmueller et al. 1979). 

IL-6 T lymphocytes, monocytes, macrophages, synovial fibroblasts Activates T lymphocytes, induces acute-phase response, stimulates growth and differentiation of hematopoietic precursor cells stimulates synovial fibroblasts... 

Progenitor cell An immature or precursor cell that can divide and give rise to a differentiated cell. 

Most mammalian cell types develop from precursor cells that divide a limited number of times before they stop and terminally differentiate. In no case do we understand why the cells stop dividing when they do. The stopping mechanisms are important because they determine how many differentiated cells are produced and when differentiation begins. We have been studying the stopping mechanism in oligodendrocyte precursor cells (OPCs) isolated from the developing optic nerve of rats and mice. 

Ahlgren SC, Wallace H, Bishop J, Neophytou C, Raff MC 1997 Effects of thyroid hormone on embryonic oligodendrocyte precursor cell development in vivo and in vitro. Mol Cell Neurosci 9 420-432... 

Kondo T, Raff M 2000b Oligodendrocyte precursor cells reprogrammed to become multipotential CNS stem cells. Science 289 1754-1757 Lane ME, Sauer K, Wallace K, Jan YN, Lehner CF, Vaessin H 1996 Dacapo, a cyclin-dependent kinase inhibitor, stops cell proliferation during Drosophila development. Cell 87 1225-1235... 

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