Figure 4.

Mmp2 Facilitates HSPC Budding and Migration via Extracellular Matrix Digestion

(A) Confocal images show fibronectin-rich ECM in the VDA (31 hpf): α-fibronectin antibody, green; DAPI (nuclei) staining, blue. Arrows point to cells between the dorsal aorta (DA) and posterior cardinal vein (PCV).

(B) High-magnification imaging of Tg(itga2b:gfp) embryos at 48 hpf shows Cd41:GFP⁺ HSPCs embedded in fibronectin-rich ECM between the DA and PCV.

(C) ARP (10 μM) treatment (12–36 hpf) increased fibronectin staining in the AGM (right) compared with controls at 36 hpf (left) (n ≥ 10 embryos/condition). Arrows mark areas of high fibronectin staining.

(D) ARP exposure (12–72 hpf) caused sustained cmyb AGM expression in WT siblings, not in fibronectin (fn1^−/−) mutants at 72 hpf. Brackets mark anterior/posterior extent of AGM region.

(E) Qualitative phenotypic distribution of embryos from (D) scored for presence or absence of cmyb in the AGM at 72 hpf (n ≥ 20/condition).

WT, wild-type. Scale bars, 20 μm (A), 10 μm (B), 30 μm (C), and 100 μm (D).