Gene expression profile during ovarian folliculogenesis

Assisted reproductive technologies have progressed significantly and have provided successful treatment for many infertile couples. However, more advanced technologies are required for severe infertility such as premature ovarian failure and ovarian impairment due to adjuvant therapy for cancer. Ovarian tissue cryopreservation followed by in vitro growth of isolated follicles is a feasible proposition for such patients. Close coordination of communication among follicle cells including oocytes, granulosa and theca cells is required for follicle growth. Crucial factors may regulate the gonadotropin-independent and -dependent follicle growth stages. To facilitate development of a culture system for early growing follicles, DNA microarray analysis of mouse ovaries recovered at 7, 10, 13, 16 and 19 days of age was performed to identify factors required for the growth of early-stage follicles. These studies showed strong intensity of zona pellucida glycoproteins, bone morphogenic protein-15 (BMP-15) and growth differentiation factor (GDF-9) in 7 days old mice, which gradually declined in 19 days old mice. KIT, KIT ligand, anti-müllerian hormone (AMH) and platelet-derived growth factor (PDGF), known as granulosa cell secreted factors, also showed relatively high expression. These studies will facilitate our understanding of the regulatory factors involved in folliculogenesis and thereby enable establishment of in vitro culture system for ovarian follicles.