TGFβ1 induces in-vitro and ex-vivo angiogenesis through VEGF production in human ovarian follicular fluid-derived granulosa cells during in-vitro fertilization cycle

•TGFβ1 is found in IVF patients’ follicular fluid (FF) and its level is sufficient to be physiologically active.•TGFβ1 causes angiogenesis via follicular granulosa cells (GCs)-mediated VEGF induction and secretion.•The cellular signaling pathways for VEGF production in GCs are TGFβR, Smad2/3, PI3 K/Akt, and JNK1/2.•The FF TGFβ1, GCs, and VEGF act in concert to cause follicular angiogenesis in human IVF cycle.