Genetic lineage tracing has been widely used for studying in vivo cell fate plasticity during embryogenesis, tissue homeostasis, and disease development. Recent applications with multiple site-specific recombinases have been used in complex and sophisticated genetic fate mapping studies. However, the previous multicolor reporters for dual recombinases had limitations of precise in situ quantification of cell number, which is mainly due to the intermingling of cells in condensed tissues. Here, we generated a dual recombinase-mediated nuclear-localized GFP and tdTomato reporter line, which enables clear, simultaneous quantification of two distinct cell lineages in vivo. Combining this dual genetic reporter with Tbx18-Cre and Cdh5-Dre lines, which genetically trace epicardial and endothelial cells, respectively, we obtained high-resolution images for the anatomic distribution of the descendants of these two distinct cell lineages in the valve mesenchyme during development, remodeling, and maturation stages. This new dual genetic reporter is expected to facilitate fate tracing of two cell lineages and their objective quantification in vivo.

遗传谱系追踪已广泛用于研究胚胎发生，组织稳态和疾病发展过程中的体内细胞命运可塑性。具有多种位点特异性重组酶的最新应用已用于复杂和复杂的遗传命运图谱研究中。然而，先前的双重重组酶的多色报告基因具有精确的原位定量细胞数量的局限性，这主要是由于细胞在浓缩组织中的混杂。在这里，我们生成了一个双重重组酶介导的核定位的GFP和tdTomato报告基因系，它能够对体内两个不同的细胞谱系进行清晰，同时的定量。结合这种双重遗传记者与Tbx18-Cre重组酶和Cdh5-Dre系，分别遗传追踪心外膜和内皮细胞，我们获得高分辨率图像，用于显示在瓣膜间质中这两个不同细胞谱系的后代在发育，重构和成熟阶段的解剖分布。这个新的双遗传记者有望促进两种细胞谱系的命运追踪及其在体内的客观定量。