Phenotypic analysis of E18.5 hearts with epicardial misexpression of human <i>TBX2</i>.

<p>(A) Histological analysis (n = 2) by hematoxylin and eosin staining of transverse sections of <i>Tbx18</i>^<i>cre/+</i><i>;Hprt</i>^{<i>CAG</i>::<i>TBX2/y</i>} hearts reveals pericardial defects (black arrow) but no further anomalies compared to the control (<i>Tbx18</i>^<i>cre/+</i>). Scale bars are 500 μm. (B-D) Immunofluorescence analysis (n = 4) of indicated proteins on transverse sections of <i>Tbx18</i>^<i>cre/+</i> (control) and <i>Tbx18</i>^<i>cre/+</i><i>;Hprt</i>^{<i>CAG</i>::<i>TBX2/y</i>} hearts. Shown are magnified regions of the right ventricle. Scale bars are 100 μm. (B) Human TBX2 protein and TAGLN is found in the epicardium and in epicardium-derived cells in <i>Tbx18</i>^<i>cre/+</i><i>;Hprt</i>^{<i>CAG</i>::<i>TBX2/y</i>} hearts. Note that the level of human TBX2 expression is similar to the level of endogenous mouse TBX2 protein. (C) Coronary vessels are surrounded by ACTA2- and TAGLN-expressing SMCs in <i>Tbx18</i>^<i>cre/+</i><i>;Hprt</i>^{<i>CAG</i>::<i>TBX2/y</i>} hearts at E18.5, but additional ACTA2- and TAGLN-positive cells are detected in the myocardium of these hearts. (D) Small EMCN-positive coronary vessels form in comparable densities in <i>Tbx18</i>^<i>cre/+</i><i>;Hprt</i>^{<i>CAG</i>::<i>TBX2/y</i>} and control hearts. Intramyocardial deposition of POSTN was detected in both genotypes in a comparable fashion. CAr, coronary artery; Epi, epicardium; LV, left ventricle; Peri, pericardium; RA, right atrium; RV, right ventricle.