Fig. 3. pig-1 regulates additional neuroblast lineages. (A-D) Neurons were identified as described in the Materials and methods. The number of lineages scored per genotype is shown in parentheses; ND, not determined. (A) pig-1 mutants have extra AVM, PVM and SDQ neurons, all descendants of the Q.p neuroblast. (B) pig-1 mutants have extra AQR and PQR neurons, and extra M4 neurons. (C) pig-1 mutants have extra I2 neurons. The average number of I2 neurons per lineage is shown above the bars of the histogram. (D) pig-1 mutants have extra PLMs and mutations in pig-1 are epistatic to mutations in ham-1. As in the HSN/PHB lineage, mutations in pig-1 interact synergistically with mutations in the pro-apoptotic genes ced-3 and egl-1 to control the penetrance of extra neurons in the Q.p (A), I2 (C) and PLM/ALN (D) lineages. (We did not examine pig-1 interactions with ced-3 or egl-1 in the lineages that produce the A/PQR and M4 neurons.)