Practice question

First cleavage in Caenorhabditis elegans partitions distinct cytoplasmic contents into AB and P1 blastomeres. P1 inherits PAR proteins, germ granules and maternal determinants like SKN-1 that autonomously activate endomesoderm gene regulatory networks, enabling isolated P1 to generate its normal repertoire of muscle, intestine and germline derivatives. AB alone produces only hypodermis and neurons, lacking pharyngeal lineages that require GLP-1/Notch signaling induced by P1 contact. This dichotomy illustrates that P1 fate is autonomously specified through inherited determinants, while AB lineage depends partially on conditional induction, highlighting mixed strategies within same embryo.