The installation of m6A on mRNA is completed by m6A methyltransferase, mainly including METTL3, METTL14, METTL16, WTAP and ZC3H13; the reversal of m6A is achieved by the two demethylation transferases, FTO and ALKBH5; m6A works mainly through YTH domain proteins, of which YTHDC1 is related to the exportation and splicing of RNA, YTHDC2 is related to the stability of RNA, YTHDF2 is related to the degradation of RNA, YTHDF1 and YTHDF3 are related to the translation of RNA.

The m5C modification is installed on mRNA by the methyltransferase which including NSUN family proteins and DNMT2. The RNA m5C modification may can be reversibly removed by TET family proteins. The biological functions of m5C modification are achieved by ALYREF, which affects RNA fate by regulating the RNA exportation.

Spermatogenesis mainly includes three processes, mitosis of spermatogonial stem cells, meiosis of spermatocytes and maturation of spermatozoa, and finally a spermatocyte will form four spermatozoon. The primary spermatocytes in the meiosis prophase I will go through four phases, which are leptonema, zygonema, pachynema and diplonema.

RNA modification is an indispensable component in the process of spermatogenesis, including the period of mitosis, meiosis and sperm maturation. However, there are still many functions of m6A effectors in spermatogenesis that have not yet been discovered. “?” indicates unresolved questions.