TBX-2::GFP expression was present in the both MS- and ABa-derived pharynx cells. TBX-2::GFP expression initiated at the 8E stage (staging by the number of endodermal, or E, cells), in 11 - 12 anteriorly localized pharyngeal cells. Based on position, these cells are likely to be the ABa descendants that will give rise to pharyngeal muscle cells (i.e., ABalpaaa a/p, ABalpapp a/p, ABaraaaaa, ABaraapa a/p, ABarapaa a/p, ARarapapp and ABaraapp a/p). By the 1.5-fold stage, TBX-2::GFP was expressed in
pm3,
pm5 and variably
pm4, with expression persisting throughout the larval and adult stages. Surprisingly, expression extended beyond the ABa lineage after the 1.5-fold stage. For example, only 2/6
pm5 nuclei derive from ABa but authors often observed all
pm5 cells expressing TBX-2::GFP in larvae. By the 3-fold stage authors also observed expression in pharyngeal neurons, occasionally in the posterior muscle
pm8 and in cells outside of the pharynx such as body wall muscles. Thus, TBX-2::GFP expression initiated within the ABa lineage but ultimately appeared in both ABa and MS-derived muscle cells.