During the complex process of oocyte development the primordial germ cell transitions into a viable mature egg competent for fertilization. This differentiation program relies on the timely presence of nuclear proteins such as transcription factors, chromatin-remodelling proteins and cell cycle regulators. Protein transport into and out of the nucleus is mediated in part by a class of proteins, known as the ‘karyopherins.’ Karyopherins are divided into two functionally differential groups with ‘importins’ (αs and the βs) binding specific cargo proteins in the cytoplasm for transport into the nucleus through interactions with the nuclear pore complexes; and ‘exportins’ that bind nuclear cargos for parallel transport into the cytoplasm. Karyopherins have been previously shown to be differentially expressed during mammalian spermatogenesis and so are implicated in driving male germ cell development ^1,2. We predict that regulated expression of karyopherins may also represent a mechanism for the regulation of oogenesis and folliculogenesis. To examine this hypothesis we have analysed mRNA and protein expression of various karyopherins (kpna1, kpna2, kpna3, kpna4, kpna6, kpna7, ipo1& ipo5 and xpo1) in the mouse ovary.  We have profiled karyopherin gene expressing profiling using NCBI Gene Expression Omnibus datasets and indentified changes in expression patterns for the different importins from the primordial germ cell through to the mature GV oocyte. At the protein level, immunohistochemisty and immunoblotting from embryonic, neonatal and adult ovary samples, as well as isolated GV and MII eggs has confirmed distinctive stage-specific expression patterns and changes in subcellular localisation of these proteins during the different stages of oogenesis and folliculogenesis. These karyopherin expression and localisation changes are likely to reflect changes in the access of specific protein cargos to the nucleus. Future studies will aim to identify stage-specific cargoes to provide further insight into the regulation of mammalian oogenesis and folliculogenesis.