Practice question

Two gonadal precursors Z1.ppp and Z4.aaa use Notch-mediated lateral inhibition to single out anchor cell required for uterus-vulva connection. Each expresses LIN-12 receptor and LAG-2 ligand competing for fate. When both lack LIN-12 functional receptor due to null mutation or RNA interference, negative feedback and transcriptional repression fails; neither cell receives inhibitory Notch signal to adopt ventral uterine fate and express uterine genes. Consequently both differentiate as anchor cells, each secreting LIN-3 EGF and invading basement membrane via fos-1a. This leads to double induction, duplicated vulval invaginations and disorganized egg-laying.