Required section · Section 2 of 6
Basic mental model
Hematopoietic stem cells reside in a bone marrow niche, self-renew, and give rise to mature blood lineages. A classical branch map is useful at the bench, although current lineage evidence supports a continuum of progressively biased progenitors. Use the map to orient production, not to claim that every progenitor is morphologically distinct.
Stem-cell factor supports stem and progenitor-cell survival in the marrow niche; erythropoietin promotes erythroid production and thrombopoietin supports megakaryocyte and platelet production.
Committed precursors become recognizable maturing cells, then enter blood or tissue pathways. Granulocytes can remain in a marrow reserve before release, while lymphoid stages often cannot be separated by routine morphology. Identify the lineage branch first, then use sequence features rather than one isolated feature.
Illustrative drawing — this picture was drawn rather than captured.
Use this reusable map to locate a cell before naming its stage.
Stem and progenitor pool
Marrow niche signals support survival and proliferation.
Lineage bias and commitment
A practical myeloid or lymphoid branch narrows likely maturation paths.
Recognizable precursor
Morphology changes as cells mature within a lineage.
Peripheral blood or tissue
Cells are released, circulate, or migrate according to lineage.
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