Vascular degradation of the OvCa-Chip. Confocal micrographs showing 3D cross-sectional views of the OvCa-Chip, consisting of cancer cells (blue, nuclei) and vascular endothelial lumen (green, VE-cadherin) (A), and the Control-Chip, consisting of benign control cells (blue, nuclei) and vascular endothelial lumen (green, VE-cadherin) (B), imaged every 24 hours after cancer cells were introduced into the device. Arrows: degradation of endothelium and the gaps formed as a result. Bars represent 200 µm. High-resolution confocal micrographs of the vascular endothelial monolayer showing distinct loss of VE-cadherin (green) (C) and subsequent formation of gaps over time (identified in image processing) (D). Bars represent 25 µm. The distinct increase in vascular endothelial gaps (E), and the loss over time of vascular barrier function (F) in OvCa-Chips (●) relative to Control-Chips (▪). Shaded areas in panels E and F represent the 48-hour period when tumor-vessel coculture was established. Error bars indicate the mean ± SEM; n = 3 individual experiments. Two-tailed paired Student t test. *P < .05; **P < .01.