Phosphodiesterase 3 inhibitors have additionally been studied in vitro to assess oocyte maturation in humans. Human oocytes cultured in the presence of ORG 9935 (1um) for 24 hours demonstrated a statistically significant reduction in germinal vesicle breakdown (an early marker of oocyte maturation) in comparison to control oocytes (12). However, no human in vivo models assessing oocyte maturation following treatment with a phosphodiesterase 3 inhibitor exist.