Expansion of mesodermal bands in Capitella teleta. Stages are marked in the lower left corner of each panel. Anterior is to the left for all panels. Images in A, B, D, E, I and L are in a ventral (vent) orientation;images in C, F, G, H, J and K are in a ventrolateral (vlat) or lateral (lat) orientation. The approximate position of the mouth (asterisk) is indicated. At the top is a developmental staging chart for C. teleta. (A-C,G-I) Confocal z-stack projections through embryos (Stage 3) and larvae (Stage 5, Stage 6) labeled with BODIPY FL phallacidin (green; cell outlines and muscle fibers) and anti-Histone antibody (red; nuclei). (D-F,J-L) Each diagram is drawn from the confocal z-stack projection directly above it. The pair of large posterior mesodermal cells (D) or the mesodermal bands (E, F, J-L) are shown in grey. lat: lateral; pt: prototroch; tt: telotroch vent: ventral; vlat: ventrolateral.