Conversion from spermatogonia to spermatocytes: Extracellular cues and downstream transcription network

•Spermatogonia-to-spermatocyte transition of mice is reviewed in four defined steps.•Extracellular signals and transcription factors in each step are enumerated.•Key factors are discussed in detail with the development process of each step.•Possible mechanisms, unsolved and controversial areas of key factors are presented.•Potential regulation networks for these transitions are depicted.