Abstract: Normal ovarian functions are not only controlled by the hypothalamic-pituitary-ovarian axis, but also regulated by autocine and paracrine systerms in the ovary. The coordinating roles among endocrine hormones, cytokines, growth factors and many other factors are essential for normal ovarian functions. Any dysregulation of these factors may result in ovarian dysfunction and ovarian diseases. MicroRNAs（miRNAs） are a class of non-coding single-stranded RNA molecules, which negatively regulated gene expression at post-transcriptional level and involved in a variety of physiological and pathological processes. Let-7c is one of the most widely studied miRNAs at present. Recent studies suggested that let-7c was related to the occurrence and development of tumor. In addition, let-7c regulates proliferation, differentiation and apoptosis of ovarian granulosa cells through various signal pathways, showing its important roles in follicular development, ovarian hormone synthesis and function, premature ovarian failure and ovarian cancer.

Key words: MicroRNAs, Ovarian follicle, Ovarian failure, premature, Ovarian neoplasms, let-7c