Practice question

Caenorhabditis elegans exemplifies mixed specification logic, classic mosaic yet incorporating essential conditional steps. Early divisions use autonomous segregation of maternal determinants including PAR proteins, MEX-3 and P granules for major axis formation and germline versus soma distinction. Nonetheless, certain fate decisions require precise induction: ABa needs signal from MS via GLP-1/Notch to produce pharynx, and P2 induces EMS to generate gut versus mesoderm via Wnt and Src signaling. Worm development thus combines predominantly autonomous partitioning with discrete conditional checkpoints refining lineages, creating invariant lineage while still employing cell communication for critical binary choices.