Figure 3.

Global versus local information in cell morphogenesis as revealed by grafting in Stylonychia (modified from diagram in [46]). (a) Highly schematic view of paroral structures during normal development in Stylonychia, showing paroral membrane (PM; green) flanked by fronto-ventral-transverse (FVT) cirri (red). The oral primordium is shown as a grey disc. Other ciliary structures are not shown. Left and right (by convention given from the cell's perspective) are as indicated. (b) Grafting experiment of Grimes and L'Hernault [7]. (c, d) The cell was cut lengthwise, then the right half folded over (c), thus placing the former posterior region to the left of the former anterior region (d) with the join shown as a dotted line. (e) When PM and FVT cirri form, two sets are formed, one on the left and one on the right. The set on the left has inverted chirality because the structures have an anterior-posterior order consistent with the overall cell body axis after grafting, while the left-right ordering is consistent with the local position of these structures in the right half before cutting and folding.