Spermatogenesis is a complicated and poorly understood process that relies on the precise regulation of the self-renewal and differentiation of spermatogonia. In many organisms, micro RNAs(mi RNAs) are involved in multiple developmental processes as critical regulators of transcriptional and post-transcriptional gene silencing. This study investigated the expression pattern of mi RNAs in type B spermatogonia cells(BSc) and primary spermatocytes(PSc) of mice, using a high-throughput small RNA sequencing system. The results revealed that the expression levels of Let-7 family mi RNAs were remarkably high in both cell types. Furthermore, the expression levels of mi R-21, mi R-140-3p, mi R-103, mi R-30 a, mi R-101 b and mi R-99 b were decreased during the transformation from BSc to PSc. These mi RNAs target vital genes that participate in apoptosis, cell proliferation and differentiation, junction assembly and cell cycle regulation. These results highlight the indispensable role of mi RNAs in spermatogenesis.
