Contractomere formation at a late stage of junction maturation. (A) Structured-illumination microscopy of synaptopodin and ZO-1. A z-stack is shown in X-Y, Y-Z, and X-Y axes. Left panel shows contractomeres on the apical plane. Right panel shows basal stress fibers. Arrows on Y-Z axis point to the basal plane. Scale bar is 5 μm. (B) Disintegration of periodic synaptopodin organization and the formation of contractomeres at the apical junction in mature monolayer. Left panels show the apical junction and contractomeres on the apical planes. Right panel shows basal stress fibers on the basal plane. X-Y, Y-Z, and X-Z views are shown. Basal stress fibers remain intact despite disassembly of apical stress fibers. Contractomeres are squared in yellow. Scale bar is 5 μm. (C) Live-cell structured-illuminated microscopy of synaptopodin and vinculin. Vinculin is absent from the apical junction in developing monolayer. Blue and orange boxes are higher magnification showing basal junctions and focal adhesions on the same basal focal plane. Scale bars are 2 μm. (D) Vinculin is absent from the apical junction in mature monolayer. A z-stack is shown in X-Y, X-Z, and Y-Z views. Scale bar is 5 μm.