605 Generation of Dkk4-Cre knock-in mice to study morphogenesis of ectodermal appendages

How ectodermal appendages are formed and patterned still open questions in mammalian biology. Ectodermal appendage morphogenesis is initiated during mouse embryonic development through a series of reciprocal interactions between the mesenchyme epithelium. The molecular cross-talk followed by formation histologically visible structures, which further give rise to teeth, mammary glands, sweat glands hair follicles (HFs). We have previously shown that Dickkopf 4 (Dkk4), canonical Wnt signalling pathway inhibitor, mRNA exclusively expressed placodes. In this work, we used CRISPR/Cas9 Dkk4 locus study generating Dkk4-Cre knock-in mice. To assess Cre expression, crossed mice with EGFP Cre-reporter EGFP-positive epithelial were found at different developmental stages confirming activity recapitulated expression. Unexpectedly, posterior half embryos harboured mesenchymal, adipocyte muscle cells. Because was not these populations, reasoned progenitors cells arose earlier development. agreement, lineage tracing revealed few epiblast early gastrulating (embryonic day, E6.5), correlated more presomitic mesoderm somites around mid-gestation (E9.5). Focusing on HF development, our data showed all EGFP-positive, suggesting epidermal do express also contribute HF. summary, line suitable model using lineage-tracing time-lapse imaging.