Fig. 6: Schematic showing that cumulus cell-derived TGFB1 promotes NPPC expression in the ampulla for mouse sperm migration in the oviduct.

a, b Molecular signaling (a) and cellular interaction (b) for sperm migration in the oviduct. When ovulation occurs, LH activates EGFR signaling in cumulus cells by EGF-like growth factors, and then cooperates with oocyte-derived paracrine factors (ODPF) to promote cumulus cell TGFB1 expression. TGFB1 induces NPPC production by binding to TGFBRs in the ampullary epithelial cells, and then promotes sperm migration from the isthmic reservoir to the ampulla for fertilization. AIJ, ampullary–isthmic junction.