Epigenetic regulations orchestrate embryonic development by modulating gene expression in time and space without entailing modifications to the DNA sequence. Non- coding DNA sequences known as enhancers regulate gene transcription by providing binding sites for transcription factors that interact with the gene promoter. Mutations affecting enhancers sequences are increasingly linked to known diseases. Studying these modifications could allow the identification of diseases long before the symptoms onset. For that, the regulatory trajectory of a given gene must first be characterised. Once the transcriptional activity of a gene is initiated, it is maintained active over time until transcriptional decommissioning leads to repression. To trace and isolate cells undergoing these distinct phases, a dual-colour transgenic reporter system has been developed. In this study, its ability to trace Col1a1 expression in limbs of mouse embryos was tested through the combined use of transgenics gene sensor and recorder. The interest in Col1a1 relies on its fundamental role in forming the extracellular matrix of bones, since deleting or depleting the gene lead respectively to embryonic lethality or to Osteogenesis Imperfecta, also called the brittle bone disease. Overall, the system was not completely successful in allowing the distinct isolation of cells undergoing different transcriptional phases but appeared nonetheless specific to Col1a1 expression. Moreover, the dual-colour reporter was also tested for its capacity to trace DE4 activity, a known Shox2 enhancer. However, the system appeared to be unable to trace the enhancer's activity. Nevertheless, significant improvements can be made to render this system fully functional.