Fig. 2

Nr2f1a mutant SV undergoes adaptive remodeling via proliferation of smooth muscle cells.

a Confocal images of Elnb IHC in whole hearts from WT and nr2f1a^aco fish at weekly intervals through 28 dpf. Venous pole (asterisks). Dashed lines outline the myocardium (white - ventricle, yellow - atrium). WT 21 dpf and 28 dpf images just show the atrium and venous pole. Scale bars – 200 μm. b Confocal images of IHC for Elnb on mid-sagittal sections showing the SV at 28 dpf. Bars indicate thickness. Scale bars − 100 μm. c Quantification of SV wall thickness (µm) in sections (n = 10 fish). Individual points on the graphs represent a single section averaged from 10 measurements from a single section (3 total sections per fish). 3 adjacent sections were analyzed per fish. d Confocal images of IHC for Elnb (magenta) and DAPI (blue) staining on sagittal sections showing the SV at 28 dpf. DAPI⁺ nuclei within the Elnb staining of the whole sections were counted. Boxes show the regions of the higher magnification. Dashed outline indicates the Elnb⁺ region. Scale bars – 50 μm. e Quantification of Elnb-surrounded cells (DAPI⁺ nuclei) within sections of the SV (n = 7 fish per group). 3 adjacent sections were quantified per fish. f Schematic of EdU labeling with intrathoracic injections in juvenile zebrafish. g Confocal images of sagittal sections from juvenile WT and nr2f1a^aco mutant fish showing the SV following detection of EdU (red) incorporation. Boxes indicate regions of higher magnification. Dashed outline indicates DAPI⁺ nuclei (blue) within the Elnb⁺ (magenta) tissue. Amhc (green) was used as control to mark the border of the SV. White arrowheads indicate EdU⁺ nuclei embedded in the Elnb⁺ tissue of the SV. Scale bars – 50 μm. h, i Quantification of a total number of Elnb-surrounded EdU⁺ nuclei and the proportion of Elnb-surrounded EdU⁺ to total (DAPI⁺) nuclei within sections SV (n = 7 fish per group). Individual points represent 1 section with 3 sections counted per fish. An unpaired, two-sided Student’s t-test was used to assess statistical differences between WT and nr2f1a^aco in all graphs. Comparisons marked ****p < 0.0001. Error bars represent the mean +/− SEM. Source data are provided as a Source Data file.