Dynamics and role of MicroRNAs during mammalian follicular development

Ovarian functions, which involve dynamically regulated processes of selection, recruitment and dominance, are known to be regulated by an array of genes, which are expressed in spatiotemporal manner in follicular somatic cells and gametes. This differential expression of genes in mammalian follicular cells is partly regulated by posttranscriptional gene regulators named microRNAs (miRNAs). In addition to the cellular miRNAs, growing number of evidences are available on the potential role of extracellular vesicles mediated transfer of miRNAs in follicular fluid. These extracellular vesicles are shown to be involved in cellto-cell communication within the follicular environment. The molecular messages carried by the extracellular vesicles released into extracellular space are thought to be reflections of the physiological status of the cells from where they are released. Therefore due to their structural nature and potential to cargo several physiologically relevant molecules, exosomes have a great potential to be used as markers of oocyte developmental competence in follicular environment. Here, we review large sets of literatures to show the dynamic nature of miRNAs during various stages of mammalian follicular development, oocyte growth and the role of some of the miRNAs in ovarian cell functions. Moreover, the presence of microvesicle and exosome-coupled extracellular miRNAs in mammalian follicular fluid and their potential involvement in cellto-cell communication are briefly discussed.