Fig. 3. Distribution of GUS– sector sizes among the population of 319 GUS–|GUS+ chimeras generated in this experiment. Chimeras were classified as having between 1 and 11 GUS– organ marginal regions on the basis of visual scoring. Local maxima in numbers of plants were seen at 3, 6 and 9 GUS– regions, roughly corresponding to plants that were 1/4, 1/2 or 3/4 GUS– in total organ area. Plants that are wholly GUS– (12 marginal regions GUS–) are not included because they are not apical chimeras and were not used for fate mapping.