Bone marrow command map

From one stem cell,
an entire blood system.

Tap any node for identity, function, morphology, and clinical hooks. Edge labels show dominant drivers.
stem/progenitor   myeloid   lymphoid
Pinch/drag to explore • tap nodes for details

Branch driver:
Core job
Exam hook
Morphology / marker
Clinical link
Rule of thumb: early cytokines maintain the pool; lineage-specific factors amplify committed progenitors. Labels here are dominant exam-tested signals—not exclusive single-factor switches.
SCF + FLT3-L
Stem cell factor + FLT3 ligand
HSC survival, self-renewal support and expansion of early multipotent progenitors; FLT3-L is especially important for dendritic-cell development.
SCF receptor = c-KIT (CD117)
EPO
Erythropoietin
CFU-E / proerythroblast → erythrocytes; mainly made by renal peritubular interstitial cells in response to hypoxia.
Kidney → red cells
TPO
Thrombopoietin
Megakaryocyte maturation and platelet production; mainly liver, acts via c-MPL.
Liver → platelets
G-CSF
Granulocyte CSF
Neutrophil production, maturation and marrow release; used clinically after chemotherapy and for stem-cell mobilization.
G = granulocytes, mainly neutrophils
M-CSF
Macrophage CSF
Monocyte → macrophage lineage; osteoclast development also depends on M-CSF plus RANKL.
M = monocyte/macrophage
GM-CSF
Granulocyte-macrophage CSF
Broadly expands granulocyte and monocyte progenitors; supports dendritic-cell generation in vitro.
Wider than G-CSF
IL-3
Multi-CSF
Early myeloid progenitor proliferation; supports basophil and mast-cell pathways with SCF.
Broad early myeloid support
IL-5
Eosinophil driver
Differentiation, activation and survival of eosinophils; classically linked with Th2 responses.
IL-5 keeps eos alive
IL-7
Lymphoid growth factor
Critical for early lymphoid development, especially T-cell development; supports B lineage in marrow.
IL-7 = lymphocyte heaven
IL-15
NK-cell homeostasis
NK-cell development, survival and proliferation; also supports memory CD8 T cells.
IL-15 → NK + memory CD8
IL-4 / IL-6 / IL-21
Activated lymphocyte differentiation
IL-4 promotes Th2 and IgE class switching; IL-6 supports plasma-cell survival; IL-21 from Tfh promotes germinal-center B-cell differentiation and plasma cells.
These act after lineage commitment, not at the HSC fork
Exam mode: hematopoiesis is a continuum, not a perfectly binary tree. The classic CMP/CLP diagram is useful, but modern single-cell data show lineage priming and overlapping potential.
High-yield corrections
1
Megakaryocyte and erythroid cells share MEP

TPO drives megakaryopoiesis; EPO drives erythropoiesis. Megakaryocytes become polyploid by endomitosis.

2
Platelets are fragments, not complete cells

They bud from megakaryocyte cytoplasm and are anucleate; erythrocytes also lose their nuclei before maturity.

3
Mast cells mature in tissue

They leave marrow as precursors; mature mast cells are tissue-resident. Basophils circulate and are a distinct lineage.

4
Dendritic cells have mixed developmental origins

Conventional and plasmacytoid DCs arise through dedicated DC progenitors; inflammatory monocyte-derived DCs come from monocytes.

5
Monocytes become specialized tissue macrophages

But many resident macrophage populations—microglia, Kupffer cells—are seeded embryonically and self-renew.

6
T-cell subsets arise after thymic maturation and activation

CD4 cells become Th1/Th2/Th17/Tfh/Treg under cytokine cues; these are functional subsets, not separate marrow progenitors.

7
B cells terminally differentiate after antigen exposure

Plasma cells secrete antibody; memory B cells provide rapid recall. IL-21 and Tfh help germinal-center maturation.

8
G-CSF vs GM-CSF

G-CSF is predominantly neutrophil-directed. GM-CSF has broader granulocyte–monocyte action.

Development sites
Yolk sac (early primitive) → fetal liver (major fetal site) → bone marrow (major after birth). T-cell maturation occurs in the thymus.