Primordial follicle activation related genes screening and differential expressed analysis by transcriptome sequencing in buffalo ovary after PI3K and mTOR stimulators activated

Buffaloes are mono-ovulating animals, with only about 5% of primordial follicles being fully capable of maturation into primary oocytes throughout their reproductive years. <i>In vitro</i> primordial follicle activation technology provides a new way to manipulate and utilize oocyte resources. However, <i>in vitro</i> activation of buffalo primordial follicles has not been reported. In this study, buffalo cortical strips were cultured <i>in vitro</i> and activated with PI3K and mTOR stimulators, and the proportion of activated and developed follicles was evaluated and compared between groups . Furthermore, the key genes involved in primordial follicle activation were screened using RNA sequencing. Results showed that buffalo ovarian cortex can be well preserved by being cultured <i>in vitro</i> for at least 7 days and maintain its tissue properties and follicular morphology. <i>In vitro</i>, treatment with PI3K and mTOR pathway stimulators significantly enhanced the activation efficiency of the primordial follicles. In addition,  several differentially expressed genes related to follicular development, such as IDO1, CXCL10 and CXCL6 were significantly up-regulated after stimulation. Our findings demonstrate that PI3K and mTOR stimulators can significantly promote the activation and development of buffalo follicles, and providing technical support and a theoretical basis for the optimization of <i>in vitro</i> culture technology of buffalo preantral follicles .