Effects of bone morphogenetic protein‐7 (BMP‐7) on primordial follicular growth in the mouse ovary

Previously, bone morphogenetic protein-7 (BMP-7) was suggested as a factor that may act to facilitate the transition of follicles from primordial stage to the pool of developed primary, preantral, and antral follicles (Lee et al. 2001: Biol Reprod 65:994-999.). Thus, aim of the present study was to evaluate effect(s) of BMP-7 on the primordial-primary follicle transition. Neonatal mouse ovaries were cultured in the presence or absence of 100 mIU/ml FSH with various doses of BMP-7 (0, 10, and 100 ng/ml). After 4-day culture period, number of follicles was counted and the expression of transcripts for FSH receptor (FSHR), kit ligand (KL), and c-kit was measured by RT-PCR. BMP-7 alone at 100 ng/ml concentration stimulated follicle development with concurrent increase of mRNA for FSHR. BMP-7 alone down-regulated KL expression however, the ratio between KL1 and KL2 was increased. There was no change in the c-kit mRNA expression. Results of the present study suggest that the BMP-7 is one of the factors involved in primordial-primary follicle transition in the mouse ovary and it may play a role in expression of FSHR for further follicular development.