AS events during chicken male germ cell differentiation. (a) ESCs were isolated from the blastoderm of fertile eggs at E0 (HH stage X). gPGCs were isolated from chicken gonads at E4.5 (HH stage 28–30), and SSCs were isolated from chicken testis at E18.5 (HH stage 44). (b) The overview of RNA-seq data analysis pipeline. (c) Representative model for five types of AS events, including alternative 5′ splice site (A5′), alternative 3′ splice site (A3′), exon skip (ES), retained intron (RI), and alternative exon (AE). (d) Numbers of AS events and involved genes during male chicken germ cell differentiation.