Palis Lab

Erythroid Lineage Differentiation

Immunohistochemical analysis of fetal blood

Immunohistochemical analysis of fetal blood for the
presence of embryonic globin reveals two primitive
erythroid cells: a late stage primitive erythroid precursor
(lower right) and a “pyrenocyte” (upper left).

The first hematopoietic cells to emerge during mammalian embryogenesis are "primitive" red cells that are necessary for survival and growth of the fetus. We have determined that primitive erythroid cells enter the bloodstream with the onset of cardiac contractions (McGrath at al. Blood, 2003), where they mature in a semisynchronous cohort and ultimately enucleate (Kingsley, et al. Blood, 2004) by interacting with macrophage cells (McGrath, et al. Blood, 2008). Furthermore, globin expression is dynamically regulated as primitive erythroid cells mature (Kingsley, et al. Blood, 2006). Our studies, taken together, indicate that the primitive erythroid lineage in mice is "mammalian", rather than "non-mammalian" in character, and can thus serve as an important model of mammalian erythroid differentiation. We are currently investigating global gene expression in carefully staged primary primitive and definitive erythroid cells isolated from murine embryos and fetuses.

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