Fig. 5. Following ablation of the Q lineages in H. robusta (Austin), the cleavage pattern of presumptive p blast cell clones is correlated to the contact area between the o/p bandlets. (A,B) The presumptive o and p bandlets shown here were labeled with injected rhodamine cell lineage tracer and Hoechst 33258 nuclear counterstaining. The two fluorescent signals are superimposed in A, and nuclear staining alone is shown in B. At the region where the presumptive p bandlets are in better contact with the presumptive o bandlet (between the white arrowheads in A), a presumptive p blast cell expresses the P-type cleavage pattern (white lines). In regions in which the contact area of the presumptive o and p bandlets is reduced, the presumptive p blast cell clones express an O-type cleavage pattern. See Fig. 4 for labeling of cells, and Fig. 2 for orientation. (C,D) Optical cross-sections of the germinal band shows the relative position of the m bandlet (green) and the o/p bandlets (red) in the area where the presumptive p bandlet expresses a P-type cleavage pattern (C) and in the area where the presumptive p bandlet expresses an O-type cleavage pattern (D). The contacting surface between the two o/p bandlets is marked with white arrows. Scale bar: 40 µm in A,B; 80 µm in C,D.