library_construction_protocol: OCT4-GFP positive spermatogonia were isolated from mice using FACS following enzyme digestion of testes.  Each sample contained about 1-2 X 10-4 cells.  Total RNAs were extracted from OCT4-GFP+ cells using ToTal RNA extraction kit (Tiangen, DP419).  RNA yield and purity were evaluated using a NanoDrop 1000 spectrophotometer (NanoDrop Technologies/Thermo Scientific, Waltham, MA).  Quality and integrity were determined by RBA 6000 Nano kit with a Bioanalyzer 2100 (Agilent Technology, Santa Clara, CA). cDNA libraries were prepared using Vazyme VAHTS mRNA-seq V3 Library Prep kit for Illumina (Vazyme, NR611).