B Cell Development in Fetal Liver
Embryonic development of B lymphocytes in the mouse is remarkably well programmed in time of gestation. A first wave of development in embryonic blood and placenta1,2 reaches its peak of mitogen-reactive precursors at day 12 of gestation. This is followed by a second wave in fetal liver, which reaches its peak of mitogen-reactive B cells around birth, i.e., at day 19 of gestation.3,4 This development also occurs when embryonic bodies with blood islands and beating heart cells develop in vitro from embryonic stem cells (U. Chen and F. Melchers, manuscript in preparation). Since mitogen-reactive precursors develop from embryonic stem cells with much the same time schedule in vitro as they do in vivo cell cycle times, numbers of divisions and differentiation steps along the embryonic B lymphocyte development must be tightly controlled. We have investigated B cell development in fetal liver of the mouse on the cellular and molecular level in order to understand how such ordered development in time of gestation is achieved.
KeywordsCell Development Fetal Liver Hemopoietic Stem Cell Cell Cycle Time Stromal Cell Line
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