Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs13578-021-00697-z/MediaObjects/13578_2021_697_Fig2_HTML.png)
Full functionality of sperm in vivo-derived from FGSCs was assessed by ICSI. Zygotes (A), two-cell embryos (B), four-cell embryos (C), and GFP signals in blastocysts (D, E) were observed in in vitro culture (KSOMAA medium) after ICSI with sperm isolated from the epididymal tail of recipient mice. F Strong green fluorescence signals in the offspring detected by live imaging under a Lumazone imaging system (MagBiosystems). TG: transgenic mice; WT: wild type. G GFP sequence in the offspring detected by Southern blot analysis. TG: transgenic mice; WT: wild type. H The methylation status of the DMRs of Peg10 and H19 genes in the mother (F0) and offspring (F1), as shown by bisulfite sequencing analysis. Scale bar, 50 µm