Fig. 6. Distribution, size and frequency of Egfr mutant clones in the D and V compartments. (A) Frequency of Egfr^ts clones that populate the D (black) or V (white) compartment, or both compartments (D/V, gray) as a function of temperature. Clones were induced during the first larval instar using the Minute technique, and larvae were kept at the indicated restrictive temperatures thereafter. n, total number of clones scored for each temperature condition. The percentage of Egfr^ts clones in the D compartment declines progressively as the temperature increases; conversely, the percentage of these clones rises in the V compartment. More clones are found within the D compartment than in the V compartment at the permissive temperature, reflecting the larger pool of cells from which the D compartment will arise. All clones within the wing disc were scored in this experiment. (B) Frequency of Egfr^– clones that populate the D (black) or V (white) compartment, or both compartments (D/V, gray), as a function of the time of clone induction [indicated by hours (h) AEL]. The Minute technique was used; n, total number of clones scored for each time interval. Egfr^– clones generated before the DV compartments are established during the second larval instar (approximately 48-72 hours AEL) preferentially populate the ventral compartment; clones induced thereafter frequent both compartments equally. Only clones populating the presumptive wing blade were scored in this experiment. (C) Relative sizes of Egfr^– clones shown in B (see Materials and Methods for quantitation of size); for clones that populated both compartments, the sizes of the mutant territories in the D and V compartments were scored separately and are designated, respectively as D/v (dark gray bars) and d/V (light gray bars). Egfr^– clones induced before the DV compartments contribute poorly to the D compartment, probably because most of the cells fail to activate ap and sort into the V compartment or out of the disc epithelium; clones induced thereafter contribute equally well to each compartment.

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