T/Bra::GFP expression in Gastruloids following Chi treatment (48-72h AA). Gastruloids made from T/Bra::GFP mESCs stimulated with a pulse of Chi and imaged by wide-field microscopy from 24h to 120h AA every 20 min. The 20x objective was used between 24 and 72h, followed by the 10x objective from 72h to the end of the experiment. Quantification of both the length and fluorescence as a function of time can be seen in Fig. 3D (bottom).