Heterozygotes are WT and segregate WT, Dpys which give only dead eggs, mid-larval lethals (hT1 homozygotes), males and dead eggs. Mutation in pop-1 results in the MS blastomere adopting the fate of the E blastomere. pop-1 mutant embryos have twice the amount of wild type gut and only make anterior pharynx. him-5 is outside the region balanced by hT2.