In vivo genetic cell lineage tracing reveals that oviductal secretory cells self-renew and give rise to ciliated cells.

The epithelial lining of the fallopian tube is vital for fertility, providing nutrition to gametes and facilitating their transport. It is composed of two major cell types: secretory cells and ciliated cells. Interestingly, human ovarian cancer precursor lesions primarily consist of secretory cells. It is unclear why secretory cells are the dominant cell type in these lesions. Additionally, the underlying mechanisms governing fallopian tube epithelial homoeostasis are unknown. In the present study, we showed that across the different developmental stages of mouse oviduct, secretory cells are the most frequently dividing cells of the oviductal epithelium. In vivo genetic cell lineage tracing showed that secretory cells not only self-renew, but also give rise to ciliated cells. Analysis of a Wnt reporter mouse model and various Wnt target genes showed that the Wnt signaling pathway is involved in oviductal epithelial homoeostasis. By developing two triple-transgenic mouse models, we showed that Wnt/β-catenin signaling is essential for self-renewal as well as the differentiation of secretory cells. In summary, our results provide mechanistic insight into oviductal epithelial homoeostasis.