Figure 3.

Connective tissue phenotype mast cells (MC_TCs) promote the initiation of endothelial cell-cell contacts during tube formation. A: Representative, color-enhanced images of fetal human pulmonary microvascular endothelial cells (feHPMVCs) undergoing tube morphogenesis when cultured for 2 hours alone and with MC_TCs or mucosal phenotype mast cells (MC_Ts). Representative feHPMVC cell-cell junctions are highlighted. No MC (control) is labeled in blue, MC_TC co-culture is labeled in red, and MC_T co-culture is labeled in green. Red arrows indicate representative MC_TC human mast cell lines (LUVAs); green arrows, representative MC_T LUVAs. B: Quantification of the frequency of cell-cell junctions containing <5 cells or ≥5 cells in each condition. C: Quantification of the total number of junctions in each condition. n = 3 (and in triplicates). ∗P < 0.05, ∗∗P < 0.01 (t-test); ^††††P < 0.0001 versus control (χ² test). Scale bars = 500 μm.