[Contribution of Tissue Hypoxia to Corpus Luteum Formation]

Corpus luteum is a temporary endocrine organ that is formed and regressed during the female reproductive cycle.It is developed from the residual follicular tissue after ovulation,which is associated with the rapid angiogenesis.Vascular endothelial growth factor(VEGF)is the most important stimulatory factor that regulates the luteal angiogenesis and also plays a key role during corpus luteum formation.VEGF is regulated by hypoxia-inducible factor(HIF)-1,which is a heterodimeric transcription factor consistent of HIF-1α and HIF-1β.The local hypoxia of ovary due to the ruptured follicle and the lack of new vascular networks induces HIF-1α expression and participates in the luteal formation through VEGF-dependent angiogenesis.The present article describes the functional and structural changes during the luteal formation from the local and hypoxic conditions immediately before and after ovulation,with an attempt to clarify the roles of hypoxia in luteal formation as well as ovarian physiology.