The development of mouse trophoblast cells at the single cell level

The placenta is a poorly understood yet vital support organ. Transcriptome analysis at single cell resolution can help us understand cell compositions, developmental processes, and physiological functions. Both mice and humans have the hemochorial placenta. Profiling the single cell transcriptome of the mouse placenta is necessary for deepening our knowledge of mammalian placentation.We systematically profiled single cell transcriptomes of mouse placentae every day from E7.5 to E14.5. After stringent filtering, 15682 mouse trophoblast cells were subjected to following transcriptome analysis. We noted that trophoblast cells underwent 3 main differentiation stages: E7.5-E8.5, E9.5-E10.5, and E11.5-E14.5. With the help of advanced computational technologies from Velocyto, PAGA, monocle, and SCENIC, we have updated the recognitions of several developmental events. Firstly, P-TGCs are suggested to only derive from EPC like cells. Secondary, sinusoid trophoblast and spongiotrophoblast all derived from EPC cells, and their cell fates have been determined before the chorioallantoic fusion. Sinusoid trophoblast cells were not derived from chorion. Thirdly, SpA-TGCs were suggested to be differentiated from spongiotrophoblast cells via Gly-T cells. Furthermore, new transcription factors have been found to play roles during the differentiation of trophoblast cells. Lastly, the expression of Ifnlr1 in chorion branch cells gradually increased during placentation, which reconfirmed that mature placenta can defend the Zika virus (ZIKV) through IFN signaling. We clarified the developmental histories of mouse trophoblast cells at the branch level, especially the differentiation of sinusoid branch trophoblast cells. Meanwhile, we offered a convincing data resource for the study of mammalian placentation and etiology analysis of pregnancy-associated diseases. Single cell transcriptomes of mouse placentae that were collected at one-day intervals between E7.5 and E14.5 NOTE: The MPL39603-*.csv,MTR15682-*.csv, UMAP-MPL39603.csv, UMAP-MTR15682.csv, UMAP-MTR-E78-3529.csv files (included in the 10x_V*_processed_data.tar.gz) belong to the GSM4725071 - GSM4725071, and V3MPL30518-*.csv, V3MTR8067-*.csv files belong to the GSM6744596 - GSM6744600 samples.