tbx-2 transcripts was detected starting at the 4E stage (~102 cell stage, 143 min after the 4-cell stage), and with mid-gastrula expression observed by in situ hybridization (Shin-i and Kohara, http://nematode.lab.nig.ac.jp/).
The egl-27 reporter is expressed in the Y cell in the 1.5-fold embryonic stage as well as during the L1 larval stage, which precedes the initiation of Y transdifferentiation.