English: Wild type mesoderm on BCR (ectoderm). Cells within the tissue move together and are tightly apposed. Adjacent cells at the boundary continuously make and break contacts. At sites of contacts across the boundary, cells move in concert indicating that cells have established stable adhesion. At sites of retraction, membranes of the mesoderm cells show wrinkles. Retraction fibers are observed during detachment. Asterisk indicates a gap within the mesoderm explants. Note that cells do not detach, but instead close the gap, showing protrusive activity.