Developmental analyses of mouse embryos and adults using a non-overlapping tracing system for all three germ layers

Development. 2019 Nov 4;146(21):dev174938. doi: 10.1242/dev.174938.


Genetic lineage-tracing techniques are powerful tools for studying specific cell populations in development and pathogenesis. Previous techniques have mainly involved systems for tracing a single gene, which are limited in their ability to facilitate direct comparisons of the contributions of different cell lineages. We have developed a new combinatorial system for tracing all three germ layers using self-cleaving 2A peptides and multiple site-specific recombinases (SSRs). In the resulting TRiCK (TRiple Coloured germ layer Knock-in) mice, the three germ layers are conditionally and simultaneously labelled with distinct fluorescent proteins via embryogenesis. We show that previously reported ectopic expressions of lineage markers are the outcome of secondary gene expression. The results presented here also indicate that the commitment of caudal axial stem cells to neural or mesodermal fate proceeds without lineage fluctuations, contrary to the notion of their bi-potency. Moreover, we developed IMES, an optimized tissue clearing method that is highly compatible with a variety of fluorescent proteins and immunostaining, and the combined use of TRiCK mice and IMES can facilitate comprehensive analyses of dynamic contributions of all three germ layers.

Keywords: 2A peptide; Fate map; Germ layer; Lineage-tracing system; Site-specific recombinase; Tissue clearing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / metabolism
  • Cell Lineage*
  • Crosses, Genetic
  • DNA Nucleotidyltransferases / metabolism
  • Embryonic Stem Cells / cytology
  • Endoderm / cytology
  • Endothelium, Vascular / cytology
  • Female
  • Gene Expression Regulation, Developmental*
  • Gene Knock-In Techniques*
  • Genotype
  • Germ Layers / cytology*
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Heart / embryology
  • Humans
  • Imaging, Three-Dimensional
  • Liver / embryology
  • Male
  • Mesoderm / cytology
  • Mice
  • Mice, Inbred C57BL
  • Myocardium / cytology
  • Neural Plate / cytology


  • Green Fluorescent Proteins
  • DNA Nucleotidyltransferases
  • Site-specific recombinase