follicular fluid

Follicular fluid is a complex mixture of plasma-derived components and substances secreted by granulosa and theca cells. It contains steroid hormones (estradiol, progesterone), growth factors (IGF-1, EGF), gonadotropins, proteoglycans, hyaluronic acid, and antioxidants — all of which create the microenvironment critical for oocyte maturation.

Follicular fluid bathes the oocyte and its surrounding cumulus granulosa cells, supplying nutrients, signaling molecules, and hormones. The composition of follicular fluid directly influences oocyte quality, fertilization potential, and embryo development — making it a biomarker target in IVF research.

During in vitro fertilization (IVF) egg retrieval, follicular fluid is aspirated alongside the oocyte-cumulus complex using a fine needle guided by transvaginal ultrasound. The fluid is then examined in the embryology lab to locate and identify oocytes before proceeding with fertilization.