Single‐cell transcriptome analysis of male chicken germ cells reveals changes in signaling pathway‐related gene expression profiles during mitotic arrest

Mitotic arrest is necessary for the embryonic development of germ cells, and thus, it is important to understand the signaling pathways that regulate mitotic arrest. Here, we investigated the signaling pathway dynamics of male embryonic chicken germ cells during mitotic arrest by single‐cell transcriptome analysis using germ‐cell tracing models. We identified signaling pathways that change at the transcriptional level during chicken male germ‐cell development after sex determination. We found that several components of the BMP, Notch, and JAK–STAT signaling pathways were downregulated at the mitotic‐arrest stage and were reactivated 1 week after hatching when all germ cells are quiescent after entering mitotic arrest. In addition, the transcriptional levels of components of the MAPK, Hedgehog, and thyroid‐hormone signaling pathways were steadily upregulated after mitotic arrest. This suggests the cooperation of multiple signaling pathways during entry into mitotic arrest and subsequent quiescence of chicken male germ cells.