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Fig. 5
HSPCs Are Anchored to Perivascular Stromal Cells during Cell Divisions
(A) cxcl12a:DsRed2+ stromal cells (red) underlie kdrl:GFP+ ECs (green). 40 hpf embryo.
(B) Percentage of HSPCs in CHT scored by distance to nearest stromal cell (n = 168 total cells from 25 embryos).
(C) Detail of Runx:GFP+ HSPCs (green) in proximity to cxcl12a:DsRed2+ stromal cells (red). Arrowheads mark HSPCs in contact with stromal cell. Circle marks HSPC with 2 µm gap between it and stromal cell. 60 hpf embryo.
(D) Six frames selected from time-lapse Movie S6 (hr:min). Top row is a merge of Runx:GFP+ HSPC (green, middle row) and cxcl12a:DsRed2+ stromal cells (red, lower row). Proximal HSPC anchored to stromal cell (arrowhead) divides and releases distal daughter cell into circulation (arrow).
(E) Rose diagram showing division plane of HSPC oriented relative to stromal cell. Majority of divisions result in displaced daughter cell (n = 26/35 cell divisions from 22 embryos; 95% confidence interval 0.567—0.875; mean division angle of 110°). Diagrams show HSPCs dividing over stromal cell surface (45°), perpendicular to stromal cell (90°), or displaced away from stromal cell (135°). Angles may be affected by release into flow of circulation.
(F) 3D models used to measure HSPC divisions relative to stromal cells. (i) Volume rendered confocal image. (ii) 3D model showing angle measurement between attachment point on stromal cell surface and center points of proximal and distal HSPCs (example shown is 110°). (iii) Overlay of confocal image and 3D model.
Scale bars, (A) 25 µm; (C and F) 10 µm; (D) 15 µm.
Reprinted from Cell, 160, Tamplin, O.J., Durand, E.M., Carr, L.A., Childs, S.J., Hagedorn, E.J., Li, P., Yzaguirre, A.D., Speck, N.A., Zon, L.I., Hematopoietic Stem Cell Arrival Triggers Dynamic Remodeling of the Perivascular Niche, 241-252, Copyright (2015) with permission from Elsevier. Full text @ Cell