Fig. 2. Typical phenotypes of let-425 homozygotes (A-C), Nomarski images of the animals at the L3 molt stage, when the induced vulval precursors cells have divided to form four progeny. (A) Wild type, (B) homozygous let-425 mutant animals and (C) a wild-type animal affected by med-6 RNAi. (D,E) Nomarski images of the vulval tissue at the L4 stage, when invagination of the induced vulval precursor cells occurs. (D) Wild type, (E) a homozygous let-425 mutant animal, showing an abnormal invagination caused by less than wild-type induction of VPCs. (F) Nomarski image of a homozygous let-425 mutant animal at the adult stage. Hypo-induced VPCs have undergone morphogenesis and formed a protruding vulva. Scale bar: 25 µm.