Abstract: Cell-culture devices and methods for determining the integrity of cell-cell adhesion are described. A cell culture device includes a channel-defining body that defines a plurality of channels in a cell-culture dish and a removable mask located above the channel-defining body. Channels of the cell-culture dish can be seeded and maintained under conditions in which a cell sheet can be formed in each of the channels. The mask defines test regions of cell sheets when cell sheets are present within the channels. A cell-substrate cleaving solution can be applied to the test regions to lift the cell sheet in the test region, causing the inherent tension due to cell spreading to be borne solely by the cell-cell junctions, such that the integrity of the cell sheets can be observed. The tension in the lifted cell sheet can be controlled by controlling the vertical design width of the channel on either side of the constriction included in the test region.