Fig. 8
Trabecular tbx5a-derived cardiomyocytes within the cortical myocardium express the cortical marker Xirp2a. Immunofluorescence with anti-Xirp2a and GFP and anti-Myosin Heavy Chain (MHC) on ventricle sections. a–f Uninjured adult tbx5a:GFP ventricle. Xirp2a expression was observed in the cortical layer but not in the trabecular layer showing a complementary pattern with tbx5a:GFP as predicted by the RNA-Seq (n = 3/3). g–r Double transgenic tbx5a:mCherry-p2a-CreERT2;ubb:loxP-lacZ-loxP-GFP were treated with 4-Hydroxytamoxifen (4-OHT) from 84 to 72 and 60 to 48 hours before cryoinjury. Hearts were fixed at 90 days postinjury (dpi). GFP+ cells marking the tbx5a lineage within the cortical layer were positive for Xirp2a, whereas GFP+ cells within the trabecular layer did not express this marker (n = 6/6). at, atrium; ba, bulbus arteriosus; v, ventricle. Scale bars, a, g 100 µm, c, m 25 μm, and h, n 10 µm